Organic Compound, Light-Emitting Element, Light-Emitting Device, Electronic Device, and Lighting Device

ABSTRACT

Provided is a novel organic compound, a benzofuropyrimidine derivative or a benzothienopyrimidine derivative, which is an organic compound represented by General Formula (G1) below.In General Formula (G1), Q represents oxygen or sulfur. Furthermore, A is a group having 12 to 100 carbon atoms in total and includes one or more of a benzene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, a triphenylene ring, a heteroaromatic ring including a dibenzothiophene ring, a heteroaromatic ring including a dibenzofuran ring, a heteroaromatic ring including a carbazole ring, a benzimidazole ring, and a triphenylamine structure.

TECHNICAL FIELD

One embodiment of the present invention relates to an organic compound,a light-emitting element, a light-emitting device, an electronic device,and a lighting device. However, one embodiment of the present inventionis not limited to the above technical field. That is, one embodiment ofthe present invention relates to an object, a method, a manufacturingmethod, or a driving method. Alternatively, one embodiment of thepresent invention relates to a process, a machine, manufacture, or acomposition of matter. Specific examples include a semiconductor device,a display device, a liquid crystal display device, and the like.

BACKGROUND ART

A light-emitting element including an EL layer between a pair ofelectrodes (also referred to as an organic EL element) hascharacteristics such as thinness, light weight, high-speed response toinput signals, and low power consumption; thus, a display including sucha light-emitting element has attracted attention as a next-generationflat panel display.

In a light-emitting element, voltage application between a pair ofelectrodes causes, in an EL layer, recombination of electrons and holesinjected from the electrodes, which brings a light-emitting substance(organic compound) contained in the EL layer into an excited state.Light is emitted when the light-emitting substance returns to the groundstate from the excited state. The excited state can be a singlet excitedstate (S*) and a triplet excited state (T*). Light emission from asinglet excited state is referred to as fluorescence, and light emissionfrom a triplet excited state is referred to as phosphorescence. Thestatistical generation ratio thereof in the light-emitting element isconsidered to be S*:T*=1:3. Since the emission spectrum obtained from alight-emitting substance depends on the light-emitting substance, theuse of different types of organic compounds as light-emitting substancesmakes it possible to obtain light-emitting elements which exhibitvarious emission colors.

In order to improve element characteristics of such a light-emittingelement, improvement of an element structure, development of a material,and the like have been actively carried out (see Patent Document 1, forexample).

REFERENCE Patent Document

-   [Patent Document 1] Japanese Published Patent Application No.    2010-182699

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Thus, in one embodiment of the present invention, a novel organiccompound is provided. In another embodiment of the present invention, abenzofuropyrimidine derivative or a benzothienopyrimidine derivativethat is a novel organic compound is provided. In one embodiment of thepresent invention, a novel organic compound that can be used in alight-emitting element is provided. In one embodiment of the presentinvention, a novel organic compound that can be used in an EL layer of alight-emitting element is provided. In addition, a highly reliable andnovel light-emitting element using a novel organic compound of oneembodiment of the present invention is provided. In addition, a novellight-emitting device, a novel electronic device, or a novel lightingdevice is provided. Note that the description of these objects does notpreclude the existence of other objects. In one embodiment of thepresent invention, there is no need to achieve all of these objects.Objects other than these are apparent from the description of thespecification, the drawings, the claims, and the like, and objects otherthan these can be derived from the description of the specification, thedrawings, the claims, and the like.

Means for Solving the Problems

One embodiment of the present invention is a benzofuropyrimidinederivative or a benzothienopyrimidine derivative which is an organiccompound represented by General Formula (G1) below. As shown in GeneralFormula (G1) below, the organic compound has a structure which includesan unsubstituted phenyl group at the 8-position of a benzofuropyrimidineskeleton or a benzothienopyrimidine skeleton.

In the above General Formula (G1), Q represents oxygen or sulfur.Furthermore, A is a group having 12 to 100 carbon atoms in total andincludes one or more of a benzene ring, a naphthalene ring, a fluorenering, a phenanthrene ring, a triphenylene ring, a heteroaromatic ringincluding a dibenzothiophene ring, a heteroaromatic ring including adibenzofuran ring, a heteroaromatic ring including a carbazole ring, abenzimidazole ring, and a triphenylamine structure. Furthermore, R¹represents hydrogen, an alkyl group having 1 to 6 carbon atoms, asubstituted or unsubstituted monocyclic saturated hydrocarbon having 5to 7 carbon atoms, a substituted or unsubstituted polycyclic saturatedhydrocarbon having 7 to 10 carbon atoms, a substituted or unsubstitutedaryl group having 6 to 13 carbon atoms, or a substituted orunsubstituted heteroaryl group having 3 to 12 carbon atoms.

Another embodiment of the present invention is a benzofuropyrimidinederivative or a benzothienopyrimidine derivative which is an organiccompound represented by General Formula (G2) below. As shown in GeneralFormula (G2) below, the organic compound has a structure which includesan unsubstituted phenyl group at the 8-position of a benzofuropyrimidineskeleton or a benzothienopyrimidine skeleton.

In the above General Formula (G2), Q represents oxygen or sulfur.Furthermore, α represents a substituted or unsubstituted phenylenegroup, and n represents an integer of 0 to 4. In addition, Ht_(uni)represents a skeleton having a hole-transport property. Furthermore, R¹represents hydrogen, an alkyl group having 1 to 6 carbon atoms, asubstituted or unsubstituted monocyclic saturated hydrocarbon having 5to 7 carbon atoms, a substituted or unsubstituted polycyclic saturatedhydrocarbon having 7 to 10 carbon atoms, a substituted or unsubstitutedaryl group having 6 to 13 carbon atoms, or a substituted orunsubstituted heteroaryl group having 3 to 12 carbon atoms.

Another embodiment of the present invention is a benzofuropyrimidinederivative or a benzothienopyrimidine derivative which is an organiccompound represented by General Formula (G3) below. As shown in GeneralFormula (G3) below, the organic compound has a structure which includesan unsubstituted phenyl group at the 8-position of a benzofuropyrimidineskeleton or a benzothienopyrimidine skeleton.

In the above General Formula (G3), Q represents oxygen or sulfur. Inaddition, Ht_(uni) represents a skeleton having a hole-transportproperty. Furthermore, R¹ represents hydrogen, an alkyl group having 1to 6 carbon atoms, a substituted or unsubstituted monocyclic saturatedhydrocarbon having 5 to 7 carbon atoms, a substituted or unsubstitutedpolycyclic saturated hydrocarbon having 7 to 10 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 13 carbon atoms, ora substituted or unsubstituted heteroaryl group having 3 to 12 carbonatoms.

Another embodiment of the present invention is a benzofuropyrimidinederivative or a benzothienopyrimidine derivative which is an organiccompound represented by General Formula (G4) below. As shown in GeneralFormula (G4) below, the organic compound has a structure which includesan unsubstituted phenyl group at the 8-position of a benzofuropyrimidineskeleton or a benzothienopyrimidine skeleton.

In the above General Formula (G4), Q represents oxygen or sulfur. Inaddition, Ht_(uni) represents a skeleton having a hole-transportproperty. Furthermore, R¹ represents hydrogen, an alkyl group having 1to 6 carbon atoms, a substituted or unsubstituted monocyclic saturatedhydrocarbon having 5 to 7 carbon atoms, a substituted or unsubstitutedpolycyclic saturated hydrocarbon having 7 to 10 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 13 carbon atoms, ora substituted or unsubstituted heteroaryl group having 3 to 12 carbonatoms.

Note that in each of the above-described structures, the Ht_(uni) in theabove General Formulae (G2), (G3), and (G4) each independently have anyone of a pyrrole ring structure, a furan ring structure, or a thiophenering structure.

Furthermore, in each of the above-described structures, the Ht_(uni) inthe above General Formulae (G2), (G3), and (G4) are each independentlyrepresented by any one of General Formulae (Ht-1) to (Ht-26) below.

In the above General Formulae (Ht-1) to (Ht-26) above, Q representsoxygen or sulfur. Furthermore, R² to R⁷¹ each represent 1 to 4substituents and each independently represent any one of hydrogen, analkyl group having 1 to 6 carbon atoms, and a substituted orunsubstituted phenyl group. Furthermore, Ar¹ represents a substituted orunsubstituted aryl group having 6 to 13 carbon atoms.

Furthermore, another embodiment of the present invention is an organiccompound represented by any one of Structural Formulae (100), (101),(102), (117), and (200).

Another embodiment of the present invention is a light-emitting elementin which the above-described organic compound of one embodiment of thepresent invention is used. The present invention also includes alight-emitting element including a guest material in addition to theabove-described organic compound.

Another embodiment of the present invention is a light-emitting elementin which the above-described organic compound of one embodiment of thepresent invention is used. Note that the present invention also includesa light-emitting element that is formed using the organic compound ofone embodiment of the present invention for an EL layer between a pairof electrodes or a light-emitting layer included in the EL layer. Inaddition to the aforementioned light-emitting elements, the presentinvention includes a light-emitting element including a layer (e.g., acap layer) that is in contact with an electrode and contains an organiccompound. In addition to the light-emitting elements, a light-emittingdevice including a transistor, a substrate, and the like is alsoincluded in the scope of the invention. Furthermore, in addition to thelight-emitting device, an electronic device and a lighting device thatinclude a microphone, a camera, an operation button, an externalconnection portion, a housing, a cover, a support, a speaker, or thelike are also included in the scope of the invention.

In addition, the scope of one embodiment of the present inventionincludes a light-emitting device including a light-emitting element, anda lighting device including the light-emitting device. Accordingly, thelight-emitting device in this specification refers to an image displaydevice or a light source (including a lighting device). In addition, alight-emitting device includes a module in which a light-emitting deviceis connected to a connector such as an FPC (Flexible printed circuit) ora TCP (Tape Carrier Package), a module in which a printed wiring boardis provided on the tip of a TCP, or a module in which an IC (integratedcircuit) is directly mounted on a light-emitting element by a COG (ChipOn Glass) method.

Effect of the Invention

In one embodiment of the present invention, a novel organic compound canbe provided. In another embodiment of the present invention, abenzofuropyrimidine derivative or a benzothienopyrimidine derivativethat is a novel organic compound can be provided. In one embodiment ofthe present invention, a novel organic compound that can be used in alight-emitting element can be provided. In one embodiment of the presentinvention, a novel organic compound that can be used in an EL layer of alight-emitting element can be provided. In addition, a highly reliableand novel light-emitting element can be provided by using a novelorganic compound of one embodiment of the present invention. Inaddition, a novel light-emitting device, a novel electronic device, or anovel lighting device can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 Drawings illustrating structures of light-emitting elements.

FIG. 2 Drawings illustrating light-emitting devices.

FIG. 3 Drawings illustrating a light-emitting device.

FIG. 4 Drawings illustrating electronic devices.

FIG. 5 Drawings illustrating an electronic device.

FIG. 6 Drawings illustrating an automobile.

FIG. 7 Drawings illustrating lighting devices.

FIG. 8 A ¹H-NMR chart of an organic compound represented by StructuralFormula (100).

FIG. 9 Ultraviolet-visible absorption spectra and emission spectra ofthe organic compound represented by Structural Formula (100).

FIG. 10 A ¹H-NMR chart of an organic compound represented by StructuralFormula (101).

FIG. 11 Ultraviolet-visible absorption spectra and emission spectra ofthe organic compound represented by Structural Formula (101).

FIG. 12 A ¹H-NMR chart of an organic compound represented by StructuralFormula (102).

FIG. 13 A ¹H-NMR chart of an organic compound represented by StructuralFormula (200).

FIG. 14 A drawing illustrating a light-emitting element.

FIG. 15 A graph showing current density-luminance characteristics of alight-emitting element 1, a comparative light-emitting element 2, and acomparative light-emitting element 3.

FIG. 16 A graph showing voltage-luminance characteristics of thelight-emitting element 1, the comparative light-emitting element 2, andthe comparative light-emitting element 3.

FIG. 17 A graph showing luminance-current efficiency characteristics ofthe light-emitting element 1, the comparative light-emitting element 2,and the comparative light-emitting element 3.

FIG. 18 A graph showing voltage-current characteristics of thelight-emitting element 1, the comparative light-emitting element 2, andthe comparative light-emitting element 3.

FIG. 19 A graph showing emission spectra of the light-emitting element1, the comparative light-emitting element 2, and the comparativelight-emitting element 3.

FIG. 20 A graph showing reliability of the light-emitting element 1, thecomparative light-emitting element 2, and the comparative light-emittingelement 3.

FIG. 21 A graph showing current density-luminance characteristics of alight-emitting element 4 and a comparative light-emitting element 5.

FIG. 22 A graph showing voltage-luminance characteristics of thelight-emitting element 4 and the comparative light-emitting element 5.

FIG. 23 A graph showing luminance-current efficiency characteristics ofthe light-emitting element 4 and the comparative light-emitting element5.

FIG. 24 A graph showing voltage-current characteristics of thelight-emitting element 4 and the comparative light-emitting element 5.

FIG. 25 A graph showing emission spectra of the light-emitting element 4and the comparative light-emitting element 5.

FIG. 26 A graph showing reliability of the light-emitting element 4 andthe comparative light-emitting element 5.

FIG. 27 A graph showing current density-luminance characteristics of alight-emitting element 6, a comparative light-emitting element 7, and acomparative light-emitting element 8.

FIG. 28 A graph showing voltage-luminance characteristics of thelight-emitting element 6, the comparative light-emitting element 7, andthe comparative light-emitting element 8.

FIG. 29 A graph showing luminance-current efficiency characteristics ofthe light-emitting element 6, the comparative light-emitting element 7,and the comparative light-emitting element 8.

FIG. 30 A graph showing voltage-current characteristics of thelight-emitting element 6, the comparative light-emitting element 7, andthe comparative light-emitting element 8.

FIG. 31 A graph showing emission spectra of the light-emitting element6, the comparative light-emitting element 7, and the comparativelight-emitting element 8.

FIG. 32 A graph showing reliability of the light-emitting element 6, thecomparative light-emitting element 7, and the comparative light-emittingelement 8.

FIG. 33 A ¹H-NMR chart of an organic compound represented by StructuralFormula (117).

FIG. 34 A graph showing current density-luminance characteristics of alight-emitting element 9.

FIG. 35 A graph showing voltage-luminance characteristics of thelight-emitting element 9.

FIG. 36 A graph showing luminance-current efficiency characteristics ofthe light-emitting element 9.

FIG. 37 A graph showing voltage-current characteristics of thelight-emitting element 9.

FIG. 38 A graph showing an emission spectrum of the light-emittingelement 9.

MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention are described in detail below withreference to drawings. Note that the present invention is not limited tothe following description, and the modes and details of the presentinvention can be modified in various ways without departing from thespirit and scope of the present invention. Thus, the present inventionshould not be construed as being limited to the descriptions in thefollowing embodiments.

Note that the position, size, range, or the like of each componentillustrated in drawings and the like is not accurately represented insome cases for easy understanding. Therefore, the disclosed invention isnot necessarily limited to the position, size, range, or the likedisclosed in drawings and the like.

Furthermore, when describing the structures of the invention withreference to the drawings in this specification and the like, thereference numerals denoting the same components are commonly used indifferent drawings.

Embodiment 1

In this embodiment, organic compounds of embodiments of the presentinvention will be described. An organic compound of one embodiment ofthe present invention is a benzofuropyrimidine derivative or abenzothienopyrimidine derivative represented by General Formula (G1)below. The organic compound which is one embodiment of the presentinvention has a structure which includes an unsubstituted phenyl groupat the 8-position of a benzofuropyrimidine skeleton or abenzothienopyrimidine skeleton as shown in General Formula (G1) below.

In General Formula (G1), Q represents oxygen or sulfur. Furthermore, Ais a group having 12 to 100 carbon atoms in total and includes one ormore of a benzene ring, a naphthalene ring, a fluorene ring, aphenanthrene ring, a triphenylene ring, a heteroaromatic ring includinga dibenzothiophene ring, a heteroaromatic ring including a dibenzofuranring, a heteroaromatic ring including a carbazole ring, a benzimidazolering, and a triphenylamine structure. Furthermore, R¹ representshydrogen, an alkyl group having 1 to 6 carbon atoms, a substituted orunsubstituted monocyclic saturated hydrocarbon having 5 to 7 carbonatoms, a substituted or unsubstituted polycyclic saturated hydrocarbonhaving 7 to 10 carbon atoms, a substituted or unsubstituted aryl grouphaving 6 to 13 carbon atoms, or a substituted or unsubstitutedheteroaryl group having 3 to 12 carbon atoms.

Another embodiment of the present invention is an organic compoundrepresented by General Formula (G2) below.

In the above General Formula (G2), Q represents oxygen or sulfur.Furthermore, α represents a substituted or unsubstituted phenylenegroup, and n represents an integer of 0 to 4. In addition, Ht_(uni)represents a skeleton having a hole-transport property. Furthermore, R¹represents hydrogen, an alkyl group having 1 to 6 carbon atoms, asubstituted or unsubstituted monocyclic saturated hydrocarbon having 5to 7 carbon atoms, a substituted or unsubstituted polycyclic saturatedhydrocarbon having 7 to 10 carbon atoms, a substituted or unsubstitutedaryl group having 6 to 13 carbon atoms, or a substituted orunsubstituted heteroaryl group having 3 to 12 carbon atoms.

Another embodiment of the present invention is an organic compoundrepresented by General Formula (G3) below.

In the above General Formula (G3), Q represents oxygen or sulfur. Inaddition, Ht_(uni) represents a skeleton having a hole-transportproperty. Furthermore, R¹ represents hydrogen, an alkyl group having 1to 6 carbon atoms, a substituted or unsubstituted monocyclic saturatedhydrocarbon having 5 to 7 carbon atoms, a substituted or unsubstitutedpolycyclic saturated hydrocarbon having 7 to 10 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 13 carbon atoms, ora substituted or unsubstituted heteroaryl group having 3 to 12 carbonatoms.

Another embodiment of the present invention is an organic compoundrepresented by General Formula (G4) below.

In the above General Formula (G4), Q represents oxygen or sulfur. Inaddition, Ht_(uni) represents a skeleton having a hole-transportproperty. Furthermore, R¹ represents hydrogen, an alkyl group having 1to 6 carbon atoms, a substituted or unsubstituted monocyclic saturatedhydrocarbon having 5 to 7 carbon atoms, a substituted or unsubstitutedpolycyclic saturated hydrocarbon having 7 to 10 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 13 carbon atoms, ora substituted or unsubstituted heteroaryl group having 3 to 12 carbonatoms.

Note that Ht_(uni) in the above General Formulae (G2), (G3), and (G4)each independently have any one of a pyrrole ring structure, a furanring structure, or a thiophene ring structure.

In addition, Ht_(uni) in General Formulae (G2), (G3), and (G4) above areeach independently represented by any one of General Formulae (Ht-1) to(Ht-26) below.

In General Formulae (Ht-1) to (Ht-26) above, Q represents oxygen orsulfur. Furthermore, R² to R⁷¹ each represent 1 to 4 substituents andeach independently represent any one of hydrogen, an alkyl group having1 to 6 carbon atoms, and a substituted or unsubstituted phenyl group.Furthermore, Ar′ represents a substituted or unsubstituted aryl grouphaving 6 to 13 carbon atoms.

Note that in the case where the substituted or unsubstituted monocyclicsaturated hydrocarbon having 5 to 7 carbon atoms, the substituted orunsubstituted polycyclic saturated hydrocarbon having 7 to 10 carbonatoms, the substituted or unsubstituted aryl group having 6 to 13 carbonatoms, the substituted or unsubstituted heteroaryl group having 3 to 12carbon atoms, or the substituted or unsubstituted phenylene group in theabove General Formulae (G1), (G2), (G3), and (G4) has a substituent,examples of the substituent include an alkyl group having 1 to 7 carbonatoms such as a methyl group, an ethyl group, a propyl group, anisopropyl group, a butyl group, an isobutyl group, a sec-butyl group, atert-butyl group, a pentyl group, or a hexyl group, a cycloalkyl grouphaving 5 to 7 carbon atoms such as a cyclopentyl group, a cyclohexylgroup, a cycloheptyl group, or a 8,9,10-trinorbornanyl group, and anaryl group having 6 to 12 carbon atoms such as a phenyl group, anaphthyl group, or a biphenyl group.

In the case where R¹ in the above General Formulae (G1), (G2), (G3), and(G4) represents a monocyclic saturated hydrocarbon having 5 to 7 carbonatoms, specific examples thereof include a cyclopentyl group, acyclohexyl group, a 1-methylcyclohexyl group, and a cycloheptyl group.

In the case where R¹ in General Formulae (G1), (G2), (G3), and (G4)above represents a polycyclic saturated hydrocarbon having 7 to 10carbon atoms, specific examples thereof include a norbornyl group, anadamantyl group, a decalin group, and a tricyclodecyl group.

In the case where R¹ in the above General Formulae (G1), (G2), (G3), and(G4) represents an aryl group having 6 to 13 carbon atoms, specificexamples thereof include a phenyl group, an o-tolyl group, a m-tolylgroup, a p-tolyl group, a mesityl group, an o-biphenyl group, am-biphenyl group, a p-biphenyl group, a 1-naphthyl group, a 2-naphthylgroup, and a fluorenyl group.

In the case where R¹ in General Formulae (G1), (G2), (G3), and (G4)above represents an alkyl group having 1 to 6 carbon atoms, specificexamples thereof include a methyl group, an ethyl group, a propyl group,an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group,a tert-butyl group, a pentyl group, an isopentyl group, a sec-pentylgroup, a tert-pentyl group, a neopentyl group, a hexyl group, anisohexyl group, a 3-methylpentyl group, a 2-methylpentyl group, a2-ethylbutyl group, a 1,2-dimethylbutyl group, and a 2,3-dimethylbutylgroup.

In the case where R¹ in the above General Formulae (G1), (G2), (G3), and(G4) represents a heteroaryl group having 3 to 12 carbon atoms, specificexamples thereof include a triadinyl group, a pyrazinyl group, apyrimidinyl group, a pyridinyl group, a quinolinyl group, anisoquinolinyl group, a benzothienyl group, a benzofuranyl group, anindolyl group, a dibenzothienyl group, a dibenzofuranyl group, and acarbazolyl group.

Note that when R¹ in the above General Formulae (G1), (G2), (G3), and(G4) has the group represented by the above-described specific examples,the organic compound of one embodiment of the present invention has ahigh T1 level.

Next, specific structural formulae of the above-described organiccompound of one embodiment of the present invention are shown below.Note that the present invention is not limited to these formulae.

Note that the organic compounds represented by the above StructuralFormulae (100) to (123) and (200) to (206) are examples of the organiccompound represented by the above General Formula (G1), and the organiccompound of one embodiment of the present invention is not limitedthereto.

Next, a synthesis method of a benzofuropyrimidine derivative or abenzothienopyrimidine derivative, which is one embodiment of the presentinvention and represented by General Formula (G1) below, will bedescribed.

In General Formula (G1), Q represents oxygen or sulfur. Furthermore, Ais a group having 12 to 100 carbon atoms in total and includes one ormore of a benzene ring, a naphthalene ring, a fluorene ring, aphenanthrene ring, a triphenylene ring, a heteroaromatic ring includinga dibenzothiophene ring, a heteroaromatic ring including a dibenzofuranring, a heteroaromatic ring including a carbazole ring, a benzimidazolering, and a triphenylamine structure. Furthermore, R¹ representshydrogen, an alkyl group having 1 to 6 carbon atoms, a substituted orunsubstituted monocyclic saturated hydrocarbon having 5 to 7 carbonatoms, a substituted or unsubstituted polycyclic saturated hydrocarbonhaving 7 to 10 carbon atoms, a substituted or unsubstituted aryl grouphaving 6 to 13 carbon atoms, or a substituted or unsubstitutedheteroaryl group having 3 to 12 carbon atoms.

<<Method for Synthesizing Organic Compound Represented by GeneralFormula (G1)>>

A variety of reactions can be used for the synthesis of the organiccompound represented by the above General Formula (G1); for example, theorganic compound represented by General Formula (G1) can be synthesizedby a simple method shown by synthesis schemes below.

The organic compound represented by General Formula (G1) can be obtainedby the reaction of a halogen compound (A1) having a benzofuropyrimidineskeleton or a benzothienopyrimidine skeleton whose 8-position issubstituted by a phenyl group and a boronic acid compound of A (A2), asshown in a synthesis scheme (P1) below.

In the above synthesis scheme (P1), X represents a halogen and Qrepresents oxygen or sulfur. Furthermore, A is a group having 12 to 100carbon atoms in total and includes one or more of a benzene ring, anaphthalene ring, a fluorene ring, a phenanthrene ring, a triphenylenering, a heteroaromatic ring including a dibenzothiophene ring, aheteroaromatic ring including a dibenzofuran ring, a heteroaromatic ringincluding a carbazole ring, a benzimidazole ring, and a triphenylaminestructure. Furthermore, R¹ represents hydrogen, an alkyl group having 1to 6 carbon atoms, a substituted or unsubstituted monocyclic saturatedhydrocarbon having 5 to 7 carbon atoms, a substituted or unsubstitutedpolycyclic saturated hydrocarbon having 7 to 10 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 13 carbon atoms, ora substituted or unsubstituted heteroaryl group having 3 to 12 carbonatoms.

The organic compound represented by General Formula (G1) can also beobtained by the reaction of a dihalogen compound (B1) having abenzofuropyrimidine skeleton or a benzothienopyrimidine skeleton and aboronic acid compound of A (A2) and the reaction of an intermediate (B2)and a phenylboronic acid compound (B3), as shown in a synthesis scheme(P2) below.

In the above synthesis scheme (P2), X represents a halogen and Qrepresents oxygen or sulfur. Furthermore, A is a group having 12 to 100carbon atoms in total and includes one or more of a benzene ring, anaphthalene ring, a fluorene ring, a phenanthrene ring, a triphenylenering, a heteroaromatic ring including a dibenzothiophene ring, aheteroaromatic ring including a dibenzofuran ring, a heteroaromatic ringincluding a carbazole ring, a benzimidazole ring, and a triphenylaminestructure. Furthermore, R¹ represents hydrogen, an alkyl group having 1to 6 carbon atoms, a substituted or unsubstituted monocyclic saturatedhydrocarbon having 5 to 7 carbon atoms, a substituted or unsubstitutedpolycyclic saturated hydrocarbon having 7 to 10 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 13 carbon atoms, ora substituted or unsubstituted heteroaryl group having 3 to 12 carbonatoms. In addition, B¹ represents a boronic acid, a boronic ester, acyclic-triolborate salt, or the like. As the cyclic-triolborate salt, alithium salt, a potassium salt, or a sodium salt may be used.

The organic compound represented by General Formula (G1) can also beobtained by the reaction of a trihalogen compound (C1) having abenzofuropyrimidine skeleton or a benzothienopyrimidine skeleton and aboronic acid compound of A (A2), the reaction of an intermediate (C2)and a boronic acid compound of R¹ (C3), and the reaction of anintermediate (C4) and a phenylboronic acid compound (B3), as shown in asynthesis scheme (P3) below.

In the above synthesis scheme (P3), X represents a halogen and Qrepresents oxygen or sulfur. Furthermore, A is a group having 12 to 100carbon atoms in total and includes one or more of a benzene ring, anaphthalene ring, a fluorene ring, a phenanthrene ring, a triphenylenering, a heteroaromatic ring including a dibenzothiophene ring, aheteroaromatic ring including a dibenzofuran ring, a heteroaromatic ringincluding a carbazole ring, a benzimidazole ring, and a triphenylaminestructure. Furthermore, R¹ represents hydrogen, an alkyl group having 1to 6 carbon atoms, a substituted or unsubstituted monocyclic saturatedhydrocarbon having 5 to 7 carbon atoms, a substituted or unsubstitutedpolycyclic saturated hydrocarbon having 7 to 10 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 13 carbon atoms, ora substituted or unsubstituted heteroaryl group having 3 to 12 carbonatoms. In addition, B¹ represents a boronic acid, a boronic ester, acyclic-triolborate salt, or the like. As the cyclic-triolborate salt, alithium salt, a potassium salt, or a sodium salt may be used.

Note that various kinds of the halogen compound (A1) including abenzofuropyrimidine skeleton or a benzothienopyrimidine skeleton whose8-position is substituted by a phenyl group, the boronic acid compoundof A (A2), the dihalogen compound (B1) including a benzofuropyrimidineskeleton or a benzothienopyrimidine skeleton, the intermediate (B2), thephenylboronic acid compound (B3), the trihalogen compound (C1) includinga benzofuropyrimidine skeleton or a benzothienopyrimidine skeleton, theintermediate (C2), the boronic acid compound of R¹ (C3), and theintermediate (C4) used in the above synthesis schemes (P1), (P2), and(P3) are commercially available or can be synthesized; accordingly, manykinds of the benzofuropyrimidine derivatives or benzothienopyrimidinederivatives represented by General Formula (G1) can be synthesized.Thus, the organic compound of one embodiment of the present invention ischaracterized by having numerous variations.

Described above are the organic compounds of embodiments of the presentinvention and examples of the synthesis method; however, the presentinvention is not limited thereto and the organic compound may besynthesized by another synthesis method.

The structures described in this embodiment can be used in anappropriate combination with the structures described in the otherembodiments.

Embodiment 2

In this embodiment, a light-emitting element in which the organiccompound described in Embodiment 1 is used will be described withreference to FIG. 1.

<<Basic Structure of Light-Emitting Element>>

First, a basic structure of a light-emitting element will be described.FIG. 1(A) illustrates an example of a light-emitting element including,between a pair of electrodes, an EL layer having a light-emitting layer.Specifically, the light-emitting element has a structure in which an ELlayer 103 is sandwiched between a first electrode 101 and a secondelectrode 102.

FIG. 1(B) illustrates an example of a light-emitting element with astacked-layer structure (tandem structure) in which a plurality of (twolayers, in FIG. 1(B)) EL layers (103 a and 103 b) are provided between apair of electrodes and a charge-generation layer 104 is provided betweenthe EL layers. With a tandem light-emitting element, a light-emittingdevice that can be driven at low voltage with low power consumption canbe obtained.

The charge-generation layer 104 has a function of injecting electronsinto one of the EL layers (103 a or 103 b) and injecting holes into theother of the EL layers (103 b or 103 a) when voltage is applied to thefirst electrode 101 and the second electrode 102. Thus, when voltage isapplied in FIG. 1(B) such that the potential of the first electrode 101is higher than that of the second electrode 102, the charge-generationlayer 104 injects electrons into the EL layer 103 a and injects holesinto the EL layer 103 b.

Note that in terms of light extraction efficiency, the charge-generationlayer 104 preferably has a light-transmitting property with respect tovisible light (specifically, the visible light transmittance withrespect to the charge-generation layer 104 is 40% or higher).Furthermore, the charge-generation layer 104 functions even when havinglower conductivity than the first electrode 101 or the second electrode102.

FIG. 1(C) illustrates an example of the case where the EL layer 103illustrated in FIG. 1(A) has a stacked-layer structure (which alsoapplies to the case where the EL layers (103 a and 103 b) in FIG. 1(B)have stacked-layer structures). Note that in this case, the firstelectrode 101 is regarded as functioning as an anode. The EL layer 103has a structure in which a hole-injection layer 111, a hole-transportlayer 112, a light-emitting layer 113, an electron-transport layer 114,and an electron-injection layer 115 are stacked sequentially over thefirst electrode 101. Even in the case where a plurality of EL layers areprovided as in the tandem structure illustrated in FIG. 1(B), each ELlayer has a stacked-layer structure, sequentially stacked from the anodeside as described above. When the first electrode 101 is a cathode andthe second electrode 102 is an anode, the stacking order in the EL layeris reversed.

The light-emitting layers 113 included in the EL layers (103, 103 a, and103 b) each contain an appropriate combination of a light-emittingsubstance and a plurality of substances, so that fluorescence orphosphorescence with a desired emission color can be obtained.Furthermore, the light-emitting layer 113 may have a stacked-layerstructure having different emission colors. In that case, differentmaterials may be used for the light-emitting substance and othersubstances used in each of the light-emitting layers that are stacked.Furthermore, a structure in which different emission colors can beobtained from the plurality of EL layers (103 a and 103 b) illustratedin FIG. 1(B) may be employed. Also in that case, different materials maybe used for the light-emitting substance and other substances used ineach of the light-emitting layers.

In addition, in the light-emitting element of one embodiment of thepresent invention, a structure may be employed in which light emissionobtained from the EL layers (103, 103 a, and 103 b) is resonated betweenboth of the electrodes so that the obtained light emission isintensified. For example, in FIG. 1(C), the light-emitting element canhave a micro optical resonator (microcavity) structure when the firstelectrode 101 is a reflective electrode and the second electrode 102 isa semi-transmissive and semi-reflective electrode, and light emissionobtained from the EL layer 103 can be intensified.

Note that when the first electrode 101 of the light-emitting element isa reflective electrode having a stacked-layer structure of a reflectiveconductive material and a light-transmitting conductive material(transparent conductive film), optical adjustment can be performed byadjusting the thickness of the transparent conductive film.Specifically, when the wavelength of light obtained from thelight-emitting layer 113 is λ, the distance between the first electrode101 and the second electrode 102 is preferably adjusted to around mλ/2(m is a natural number).

To amplify desired light (wavelength: λ) obtained from thelight-emitting layer 113, the optical path length from the firstelectrode 101 to a region where the desired light is obtained in thelight-emitting layer 113 (light-emitting region) and the optical pathlength from the second electrode 102 to the region where the desiredlight is obtained in the light-emitting layer 113 (light-emittingregion) are preferably adjusted to around (2m′+1)λ/4 (m′ is a naturalnumber). Here, the light-emitting region refers to a region where holesand electrons are recombined in the light-emitting layer 113.

By performing such optical adjustment, the spectrum of specificmonochromatic light obtained from the light-emitting layer 113 can benarrowed and light emission with high color purity can be obtained.

However, in the above case, the optical path length between the firstelectrode 101 and the second electrode 102 is, to be exact, the totalthickness from a reflective region in the first electrode 101 to areflective region in the second electrode 102. However, it is difficultto precisely determine the reflective regions in the first electrode 101and the second electrode 102; thus, it is assumed that the above effectcan be sufficiently obtained with given positions in the first electrode101 and the second electrode 102 being supposed to be reflectiveregions. Furthermore, the optical path length between the firstelectrode 101 and the light-emitting layer from which the desired lightis obtained is, to be exact, the optical path length between thereflective region in the first electrode 101 and the light-emittingregion in the light-emitting layer from which the desired light isobtained. However, it is difficult to precisely determine the reflectiveregion in the first electrode 101 and the light-emitting region in thelight-emitting layer from which the desired light is obtained; thus, itis assumed that the above effect can be sufficiently obtained with agiven position in the first electrode 101 being supposed to be thereflective region and a given position in the light-emitting layer fromwhich the desired light is obtained being supposed to be thelight-emitting region.

In the case where the light-emitting element illustrated in FIG. 1(C)has a microcavity structure, light (monochromatic light) with differentwavelengths can be extracted even when the same EL layer is used. Thus,separate coloring for obtaining different emission colors (e.g., R, G,and B) is not necessary, and high definition can be achieved. Inaddition, a combination with coloring layers (color filters) is alsopossible. Furthermore, emission intensity of light with a specificwavelength in the front direction can be increased, so that powerconsumption can be reduced.

A light-emitting element illustrated in FIG. 1(E) is an example of thelight-emitting element with the tandem structure illustrated in FIG.1(B), and includes three EL layers (103 a, 103 b, and 103 c) stackedwith charge-generation layers (104 a and 104 b) sandwiched therebetween,as illustrated in the drawing. Note that the three EL layers (103 a, 103b, and 103 c) include respective light-emitting layers (113 a, 113 b,and 113 c) and the emission colors of the respective light-emittinglayers can be combined freely. For example, the light-emitting layer 113a can be blue, the light-emitting layer 113 b can be red, green, oryellow, and the light-emitting layer 113 c can be blue; for anotherexample, the light-emitting layer 113 a can be red, the light-emittinglayer 113 b can be blue, green, or yellow, and the light-emitting layer113 c can be red.

In the above light-emitting element of one embodiment of the presentinvention, at least one of the first electrode 101 and the secondelectrode 102 is a light-transmitting electrode (transparent electrode,semi-transmissive and semi-reflective electrode, or the like). In thecase where the light-transmitting electrode is a transparent electrode,the visible light transmittance of the transparent electrode is 40% orhigher. In the case where the light-transmitting electrode is asemi-transmissive and semi-reflective electrode, the visible lightreflectance of the semi-transmissive and semi-reflective electrode ishigher than or equal to 20% and lower than or equal to 80%, preferablyhigher than or equal to 40% and lower than or equal to 70%. Theresistivity of these electrodes is preferably 1×10⁻² Ωcm or lower.

Furthermore, when one of the first electrode 101 and the secondelectrode 102 is a reflective electrode in the above light-emittingelement of one embodiment of the present invention, the visible lightreflectance of the reflective electrode is higher than or equal to 40%and lower than or equal to 100%, preferably higher than or equal to 70%and lower than or equal to 100%. The resistivity of this electrode ispreferably 1×10⁻² Ωcm or lower.

<<Specific Structure and Fabrication Method of Light-Emitting Element>>

Next, specific structures and fabrication methods of the light-emittingelements of embodiments of the present invention illustrated in FIG. 1will be described. Note that here, collective description is made on alight-emitting element with a tandem structure illustrated in FIG. 1(B),FIG. 1(D), and FIG. 1(E) in addition to the light-emitting element whoseEL layer 103 has a single-layer structure as illustrated in FIG. 1(A)and FIG. 1(C). In the case where the light-emitting element illustratedin FIG. 1 has a microcavity structure, the first electrode 101 is formedas a reflective electrode and the second electrode 102 is formed as asemi-transmissive and semi-reflective electrode, for example. Theelectrode can be formed, using one or more kinds of desired electrodematerials, as a single layer or a stacked layer. The second electrode102 is formed after formation of the EL layer (103 or 103 b), with theuse of a material selected as described above. For fabrication of theseelectrodes, a sputtering method or a vacuum evaporation method can beused.

<First Electrode and Second Electrode>

As materials for forming the first electrode 101 and the secondelectrode 102, any of the following materials can be used in anappropriate combination as long as the functions of the electrodesdescribed above can be fulfilled. For example, a metal, an alloy, anelectrically conductive compound, a mixture of these, and the like canbe used as appropriate. Specifically, an In—Sn oxide (also referred toas ITO), an In—Si—Sn oxide (also referred to as ITSO), an In—Zn oxide,and an In—W—Zn oxide can be given. In addition, it is also possible touse a metal such as aluminum (Al), titanium (Ti), chromium (Cr),manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu),gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo),tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt),silver (Ag), yttrium (Y), or neodymium (Nd) or an alloy containing anappropriate combination of any of these metals. It is also possible touse an element belonging to Group 1 or Group 2 in the periodic table,which is not listed above as an example (for example, lithium (Li),cesium (Cs), calcium (Ca), or strontium (Sr)), a rare earth metal suchas europium (Eu) or ytterbium (Yb), an alloy containing an appropriatecombination of any of these elements, graphene, or the like.

When the light-emitting element illustrated in FIG. 1 includes the ELlayer 103 having a stacked-layer structure as in FIG. 1(C) and the firstelectrode 101 is an anode, the hole-injection layer 111 and thehole-transport layer 112 of the EL layer 103 are sequentially stackedover the first electrode 101 by a vacuum evaporation method.Alternatively, when the plurality of EL layers (103 a and 103 b) eachhaving a stacked-layer structure are stacked with the charge-generationlayer 104 therebetween as in FIG. 1(D) and the first electrode 101 is ananode, a hole-injection layer 111 a and a hole-transport layer 112 a ofthe EL layer 103 a are sequentially stacked over the first electrode 101by a vacuum evaporation method. Furthermore, after the EL layer 103 aand the charge-generation layer 104 are sequentially stacked, ahole-injection layer 111 b and a hole-transport layer 112 b of the ELlayer 103 b are sequentially stacked over the charge-generation layer104 in a similar manner.

<Hole-Injection Layer and Hole-Transport Layer>

The hole-injection layers (111, 111 a, and 111 b) are each a layer thatinjects holes from the first electrode 101 which is an anode and thecharge-generation layer (104) to the EL layers (103, 103 a, and 103 b)and contains a material with a high hole-injection property.

As examples of the material with a high hole-injection property,transition metal oxides such as a molybdenum oxide, a vanadium oxide, aruthenium oxide, a tungsten oxide, and a manganese oxide can be given.Alternatively, it is possible to use a phthalocyanine-based compoundsuch as phthalocyanine (abbreviation: H₂Pc) or copper phthalocyanine(abbreviation: CuPc), or the like.

It is also possible to use an aromatic amine compound, which is a lowmolecular compound, such as4,4′,4″-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA),4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviation: MTDATA),4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation:DPAB),4,4′-bis(N-{4-[N-(3-methylphenyl)-N-phenylamino]phenyl}-N-phenylamino)biphenyl(abbreviation: DNTPD),1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene(abbreviation: DPA3B),3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA1),3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA2), or3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole(abbreviation: PCzPCN1).

It is also possible to use a high molecular compound (an oligomer, adendrimer, a polymer, or the like) such as poly(N-vinylcarbazole)(abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA),poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N-phenylamino}phenyl)methacrylamide](abbreviation: PTPDMA), orpoly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] (abbreviation:Poly-TPD). Alternatively, it is also possible to use a high molecularcompound to which acid is added, such aspoly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid)(abbreviation: PEDOT/PSS) or polyaniline/poly(styrenesulfonic acid)(abbreviation: PAni/PSS).

Alternatively, as the material with a high hole-injection property, acomposite material containing a hole-transport material and an acceptormaterial (electron-accepting material) can be used. In that case, theacceptor material extracts electrons from the hole-transport material,so that holes are generated in the hole-injection layers (111, 111 a,and 111 b) and the holes are injected into the light-emitting layers(113, 113 a, and 113 b) through the hole-transport layers (112, 112 a,and 112 b). Note that each of the hole-injection layers (111, 111 a, and111 b) may be formed as a single layer formed of a composite materialcontaining a hole-transport material and an acceptor material(electron-accepting material), or may be formed by stacking a layerincluding a hole-transport material and a layer including an acceptormaterial (electron-accepting material).

The hole-transport layers (112, 112 a, and 112 b) are each a layer thattransports the holes, which are injected from the first electrode 101 bythe hole-injection layers (111, 111 a, and 111 b), to the light-emittinglayers (113, 113 a, and 113 b). Note that the hole-transport layers(112, 112 a, and 112 b) are each a layer containing a hole-transportmaterial. It is particularly preferable that the HOMO level of thehole-transport material used in the hole-transport layers (112, 112 a,and 112 b) be the same as or close to the HOMO level of thehole-injection layers (111, 111 a, and 111 b).

As the acceptor material used in the hole-injection layers (111, 111 a,and 111 b), an oxide of a metal belonging to any of Group 4 to Group 8of the periodic table can be used. Specific examples include molybdenumoxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide,tungsten oxide, manganese oxide, and rhenium oxide. Among these,molybdenum oxide is especially preferable since it is stable in the air,has a low hygroscopic property, and is easy to handle. Alternatively,organic acceptors such as a quinodimethane derivative, a chloranilderivative, and a hexaazatriphenylene derivative can be used. Asexamples of ones having an electron-withdrawing group (halogen group orcyano group), 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane(abbreviation: F₄-TCNQ), chloranil,2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation:HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane(abbreviation: F6-TCNNQ), and the like can be given. A compound in whichelectron-withdrawing groups are bonded to a condensed aromatic ringhaving a plurality of hetero atoms, such as HAT-CN, is particularlypreferable because it is thermally stable. A [3]radialene derivativeincluding an electron-withdrawing group (in particular, a cyano group ora halogen group such as a fluoro group) has a very highelectron-accepting property and thus is preferred; specific examplesincludeα,α′,α″-1,2,3-cyclopropanetriylidenetris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile],α,α′,α″-1,2,3-cyclopropanetriylidenetris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile],andα,α′,α″-1,2,3-cyclopropanetriylidenetris[2,3,4,5,6-pentafluorobenzeneacetonitrile].

The hole-transport materials used in the hole-injection layers (111, 111a, and 111 b) and the hole-transport layers (112, 112 a, and 112 b) arepreferably substances with a hole mobility of higher than or equal to10⁻⁶ cm²/Vs. Note that other substances can be used as long as thesubstances have a hole-transport property higher than anelectron-transport property.

As the hole-transport material, materials having a high hole-transportproperty, such as a π-electron rich heteroaromatic compound (e.g., acarbazole derivative, a furan derivative, and a thiophene derivative)and an aromatic amine (compound having an aromatic amine skeleton), arepreferred.

Examples of the above carbazole derivative (a compound having acarbazole skeleton) include a bicarbazole derivative (e.g., a3,3′-bicarbazole derivative) and an aromatic amine having a carbazolylgroup.

Note that specific examples of the bicarbazole derivative (e.g., a3,3′-bicarbazole derivative) include 3,3′-bis(9-phenyl-9H-carbazole)(abbreviation: PCCP), 9,9′-bis(1,1′-biphenyl-4-yl)-3,3′-bi-9H-carbazole,9,9′-bis(1,1′-biphenyl-3-yl)-3,3′-bi-9H-carbazole,9-(1,1′-biphenyl-3-yl)-9′-(1,1′-biphenyl-4-yl)-9H,9′H-3,3′-bicarbazole(abbreviation: mBPCCBP),9-(2-naphthyl)-9′-phenyl-9H,9′H-3,3′-bicarbazole (abbreviation: βNCCP).

Specific examples of the aromatic amine having a carbazolyl groupinclude 4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBA1BP),N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine(abbreviation: PCBiF),N-(1,1′-biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine(abbreviation: PCBBiF),4,4′-diphenyl-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBBi1BP),4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBANB),4,4′-di(1-naphthyl)-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBNBB),4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviation:PCA1BP),N,N′-bis(9-phenylcarbazol-3-yl)-N,N′-diphenylbenzene-1,3-diamine(abbreviation: PCA2B),N,N′,N″-triphenyl-N,N′,N″-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine(abbreviation: PCA3B),9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine(abbreviation: PCBAF),N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9′-bifluoren-2-amine(abbreviation: PCBASF),3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA1),3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA2),3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole(abbreviation: PCzPCN1),3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzDPA1),3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzDPA2),3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole(abbreviation: PCzTPN2),2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9′-bifluorene(abbreviation: PCASF),N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation:YGA1BP),N,N′-bis[4-(carbazol-9-yl)phenyl]-N,N′-diphenyl-9,9-dimethylfluorene-2,7-diamine(abbreviation: YGA2F), and 4,4′,4″-tris(carbazol-9-yl)triphenylamine(abbreviation: TCTA).

In addition to the above, other examples of the carbazole derivativeinclude 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole(abbreviation: PCPPn), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole(abbreviation: PCPN), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP),4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP),3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP),1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), and9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA).

Specific examples of the above thiophene derivative and the furanderivative include compounds having a thiophene skeleton, such as1,3,5-tri(dibenzothiophen-4-yl)benzene (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene(abbreviation: DBTFLP-III), and4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene(abbreviation: DBTFLP-IV), and compounds having a furan skeleton, suchas 4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation:DBF3P-II) and4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran(abbreviation: mmDBFFLBi-II).

Specific examples of the above aromatic amine include4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB orα-NPD),N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1′-biphenyl]-4,4′-diamine(abbreviation: TPD),4,4′-bis[N-(spiro-9,9′-bifluoren-2-yl)-N-phenylamino]biphenyl(abbreviation: BSPB), 4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine(abbreviation: BPAFLP), 4-phenyl-3′-(9-phenylfluoren-9-yl)triphenylamine(abbreviation: mBPAFLP),N-(9,9-dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N′-phenyl-N′-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine(abbreviation: DFLADFL),N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine(abbreviation: DPNF),2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9′-bifluorene(abbreviation: DPASF),2,7-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-spiro-9,9′-bifluorene(abbreviation: DPA2SF),4,4′,4″-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation:1-TNATA), 4,4′,4″-tris(N,N′-diphenylamino)triphenylamine (abbreviation:TDATA), 4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviation: m-MTDATA),N,N′-di(p-tolyl)-N,N′-diphenyl-p-phenylenediamine (abbreviation:DTDPPA), 4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl(abbreviation: DPAB),N,N′-bis{4-[bis(3-methylphenyl)amino]phenyl}-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine(abbreviation: DNTPD), and1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene(abbreviation: DPA3B).

Furthermore, as the hole-transport material, a high molecular compoundsuch as poly(N-vinylcarbazole) (abbreviation: PVK),poly(4-vinyltriphenylamine) (abbreviation: PVTPA),poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N′-phenylamino}phenyl)methacrylamide](abbreviation: PTPDMA), orpoly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] (abbreviation:Poly-TPD) can also be used.

Note that the hole-transport material is not limited to the aboveexamples and one of or a combination of various known materials can beused as the hole-transport material for the hole-injection layers (111,111 a, and 111 b) and the hole-transport layers (112, 112 a, and 112 b).Note that the hole-transport layers (112, 112 a, and 112 b) may each beformed of a plurality of layers. That is, a first hole-transport layerand a second hole-transport layer may be stacked, for example.

In the light-emitting element illustrated in FIG. 1, the light-emittinglayer (113 or 113 a) is formed over the hole-transport layer (112 or 112a) of the EL layer (103 or 103 a) by a vacuum evaporation method. Notethat in the case of the light-emitting element with the tandem structureillustrated in FIG. 1(D), after the EL layer 103 a and thecharge-generation layer 104 are formed, the light-emitting layer 113 bis also formed over the hole-transport layer 112 b of the EL layer 103 bby a vacuum evaporation method.

<Light-Emitting Layer>

The light-emitting layers (113, 113 a, 113 b, and 113 c) each contain alight-emitting substance. Note that as the light-emitting substance, asubstance that exhibits emission color of blue, purple, bluish purple,green, yellowish green, yellow, orange, red, or the like isappropriately used. When the light-emitting layers (113 a, 113 b, and113 c) are formed using different light-emitting substances, differentemission colors can be exhibited (for example, complementary emissioncolors are combined to obtain white light emission). Furthermore, astacked-layer structure in which one light-emitting layer containsdifferent light-emitting substances may be employed.

The light-emitting layers (113, 113 a, 113 b, and 113 c) may eachcontain one or more kinds of organic compounds (a host material and thelike) in addition to a light-emitting substance (guest material). As theone or more kinds of organic compounds, the organic compound of oneembodiment of the present invention or one or both of the hole-transportmaterial and the electron-transport material described in thisembodiment can be used.

The light-emitting substance that can be used in the light-emittinglayers (113, 113 a, 113 b, and 113 c) is not particularly limited, and alight-emitting substance that converts singlet excitation energy intolight emission in the visible light range or a light-emitting substancethat converts triplet excitation energy into light emission in thevisible light range can be used.

Examples of other light-emitting substances are given below.

As an example of the light-emitting substance that converts singletexcitation energy into light emission, a substance that emitsfluorescence (fluorescent material) can be given; examples include apyrene derivative, an anthracene derivative, a triphenylene derivative,a fluorene derivative, a carbazole derivative, a dibenzothiophenederivative, a dibenzofuran derivative, a dibenzoquinoxaline derivative,a quinoxaline derivative, a pyridine derivative, a pyrimidinederivative, a phenanthrene derivative, and a naphthalene derivative. Apyrene derivative is particularly preferable because it has a highemission quantum yield. Specific examples of the pyrene derivativeincludeN,N′-bis(3-methylphenyl)-N,N′-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine(abbreviation: 1,6mMemFLPAPrn),N,N′-diphenyl-N,N′-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine(abbreviation: 1,6FLPAPrn),N,N′-bis(dibenzofuran-2-yl)-N,N′-diphenylpyrene-1,6-diamine(abbreviation: 1,6FrAPrn),N,N′-bis(dibenzothiophen-2-yl)-N,N′-diphenylpyrene-1,6-diamine(abbreviation: 1,6ThAPrn),N,N′-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-6-amine](abbreviation: 1,6BnfAPrn),N,N′-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine](abbreviation: 1,6BnfAPrn-02), andN,N′-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine](abbreviation: 1,6BnfAPrn-03).

In addition, it is possible to use5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2′-bipyridine (abbreviation:PAP2BPy), 5,6-bis[4′-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2′-bipyridine(abbreviation: PAPP2BPy),N,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine(abbreviation: YGA2S),4-(9H-carbazol-9-yl)-4′-(10-phenyl-9-anthryl)triphenylamine(abbreviation: YGAPA),4-(9H-carbazol-9-yl)-4′-(9,10-diphenyl-2-anthryl)triphenylamine(abbreviation: 2YGAPPA),N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: PCAPA),4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPA),4-[4-(10-phenyl-9-anthryl)phenyl]-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBAPBA), perylene, 2,5,8,11-tetra-tert-butylperylene(abbreviation: TBP), N,N″-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N′,N′-triphenyl-1,4-phenylenediamine](abbreviation: DPABPA),N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: 2PCAPPA),N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: 2DPAPPA), or the like.

As examples of the light-emitting substance that converts tripletexcitation energy into light emission, a substance that emitsphosphorescence (phosphorescent material) and a thermally activateddelayed fluorescence (TADF) material that exhibits thermally activateddelayed fluorescence can be given.

Examples of a phosphorescent material include an organometallic complex,a metal complex (platinum complex), and a rare earth metal complex.These substances exhibit different emission colors (emission peaks) andthus, any of them is selected and used appropriately according to need.

As a phosphorescent material that exhibits blue or green and whoseemission spectrum has a peak wavelength at greater than or equal to 450nm and less than or equal to 570 nm, the following substances can begiven.

For example, organometallic complexes having a 4H-triazole skeleton,such astris{2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-N²]phenyl-κC}iridium(III)(abbreviation: [Ir(mpptz-dmp)₃]),tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III)(abbreviation: [Ir(Mptz)₃]),tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III)(abbreviation: [Ir(iPrptz-3b)₃]), andtris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III)(abbreviation: [Ir(iPr5btz)₃]); organometallic complexes having a1H-triazole skeleton, such astris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III)(abbreviation: [Ir(Mptz1-mp)₃]) andtris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III)(abbreviation: [Ir(Prptz1-Me)₃]); organometallic complexes having animidazole skeleton, such asfac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III)(abbreviation: [Ir(iPrpmi)₃]) andtris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III)(abbreviation: [Ir(dmpimpt-Me)₃]); organometallic complexes in which aphenylpyridine derivative having an electron-withdrawing group is aligand, such asbis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)tetrakis(1-pyrazolyl)borate (abbreviation: FIr6),bis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III) picolinate(abbreviation: FIrpic),bis{2-[3′,5′-bis(trifluoromethyl)phenyl]pyridinato-N,C^(2′)}iridium(III)picolinate (abbreviation: [Ir(CF₃ppy)₂(pic)]), andbis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)acetylacetonate (abbreviation: FIr(acac)); and the like can be given.

As a phosphorescent material that exhibits green or yellow and whoseemission spectrum has a peak wavelength at greater than or equal to 495nm and less than or equal to 590 nm, the following substances can begiven.

For example, organometallic iridium complexes having a pyrimidineskeleton, such as tris(4-methyl-6-phenylpyrimidinato)iridium(III)(abbreviation: [Ir(mppm)₃]),tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation:[Ir(tBuppm)₃]),(acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III)(abbreviation: [Ir(mppm)₂(acac)]),(acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III)(abbreviation: [Ir(tBuppm)₂(acac)]),(acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III)(abbreviation: [Ir(nbppm)₂(acac)]),(acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III)(abbreviation: [Ir(mpmppm)₂(acac)]),(acetylacetonato)bis{4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN³]phenyl-κC}iridium(III)(abbreviation: [Ir(dmppm-dmp)₂(acac)]), and(acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III)(abbreviation: [Ir(dppm)₂(acac)]); organometallic iridium complexeshaving a pyrazine skeleton, such as(acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III)(abbreviation: [Ir(mppr-Me)₂(acac)]) and(acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III)(abbreviation: [Ir(mppr-iPr)₂(acac)]); organometallic iridium complexeshaving a pyridine skeleton, such astris(2-phenylpyridinato-N,C^(2′))iridium(III) (abbreviation:[Ir(ppy)₃]), bis(2-phenylpyridinato-N,C^(2′))iridium(III)acetylacetonate (abbreviation: [Ir(ppy)₂(acac)]),bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation:[Ir(bzq)₂(acac)]), tris(benzo[h]quinolinato)iridium(III)(abbreviation:[Ir(bzq)₃]), tris(2-phenylquinolinato-N,C^(2′))iridium(III)(abbreviation: [Ir(pq)₃]),bis(2-phenylquinolinato-N,C^(2′))iridium(III)acetylacetonate(abbreviation:[Ir(pq)₂(acac)]),bis[2-(2-pyridinyl-KN)phenyl-κC][2-(4-phenyl-2-pyridinyl-κN)phenyl-κC]iridium(III)(abbreviation: [Ir(ppy)₂(4dppy)]), andbis[2-(2-pyridinyl-κN)phenyl-κC][2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC];organometallic complexes such asbis(2,4-diphenyl-1,3-oxazolato-N,C^(2′))iridium(III) acetylacetonate(abbreviation: [Ir(dpo)₂(acac)]),bis{2-[4′-(perfluorophenyl)phenyl]pyridinato-N,C^(2′)}iridium(III)acetylacetonate (abbreviation: [Ir(p-PF-ph)₂(acac)]), andbis(2-phenylbenzothiazolato-N,C^(2′))iridium(III) acetylacetonate(abbreviation: [Ir(bt)₂(acac)]); and rare earth metal complexes such astris(acetylacetonato)(monophenanthroline)terbium(III) (abbreviation:[Tb(acac)₃(Phen)]) can be given.

As a phosphorescent material that exhibits yellow or red and whoseemission spectrum has a peak wavelength at greater than or equal to 570nm and less than or equal to 750 nm, the following substances can begiven.

For example, organometallic complexes having a pyrimidine skeleton, suchas(diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III)(abbreviation: [Ir(5mdppm)₂(dibm)]),bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III)(abbreviation: [Ir(5mdppm)₂(dpm)]), and(dipivaloylmethanato)bis[4,6-di(naphthalen-1-yl)pyrimidinato]iridium(III)(abbreviation: [Ir(d1npm)₂(dpm)]); organometallic complexes having apyrazine skeleton, such as(acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III)(abbreviation: [Ir(tppr)₂(acac)]),bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III)(abbreviation: [Ir(tppr)₂(dpm)]),bis{4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-5-phenyl-2-pyrazinyl-KN]phenyl-κC}(2,6-dimethyl-3,5-heptanedionato-κ²O,O′)iridium(III)(abbreviation: [Ir(dmdppr-P)₂(dibm)]),bis{4,6-dimethyl-2-[5-(4-cyano-2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-N]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κ²O,O′)iridium(III)(abbreviation: [Ir(dmdppr-dmCP)₂(dpm)]),(acetylacetonato)bis[2-methyl-3-phenylquinoxalinato-N,C^(2′)]iridium(III)(abbreviation: [Ir(mpq)₂(acac)]),(acetylacetonato)bis(2,3-diphenylquinoxalinato-N,C^(2′))iridium(III)(abbreviation: [Ir(dpq)₂(acac)]), and(acetylacetonato)bis[2,3-bis(4-fluorophenyl)quinoxalinato]iridium(III)(abbreviation: [Ir(Fdpq)₂(acac)]); organometallic complexes having apyridine skeleton, such astris(1-phenylisoquinolinato-N,C^(2′))iridium(III) (abbreviation:[Ir(piq)₃]), bis(1-phenylisoquinolinato-N,C^(2′))iridium(III)acetylacetonate (abbreviation: [Ir(piq)₂(acac)]), andbis[4,6-dimethyl-2-(2-quinolinyl-κN)phenyl-κC](2,4-pentanedionato-κ²O,O′)iridium(III);platinum complexes such as2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II)(abbreviation:[PtOEP]);and rare earth metal complexes such astris(1,3-diphenyl-1,3-propanedionato)(monophenanthroline)europium(III)(abbreviation: [Eu(DBM)₃(Phen)]) andtris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III)(abbreviation: [Eu(TTA)₃(Phen)]) can be given.

As the organic compounds (the host material and the like) used in thelight-emitting layers (113, 113 a, 113 b, and 113 c), one or more kindsof substances having a larger energy gap than the light-emittingsubstance (the guest material) are selected to be used.

Accordingly, in the case where the light-emitting substance used in thelight-emitting layer (113, 113 a, 113 b, 113 c) is a fluorescentmaterial, an organic compound (host material) used in combination withthe light-emitting substance is preferably an organic compound that hasa high energy level in a singlet excited state and has a low energylevel in a triplet excited state. Note that as the organic compound(host material) used in combination with the light-emitting substance,not only the organic compound described in Embodiment 1, which is oneembodiment of the present invention, or the hole-transport material(described above) or an electron-transport material (described later),which are described in this embodiment, but also a bipolar material orthe like can be used. When the organic compound described in Embodiment1, which is one embodiment of the present invention, is used in alight-emitting layer (especially when used as a host material), initialdegradation of the light-emitting element can be suppressed, leading tohigher reliability.

In terms of a preferable combination with a light-emitting substance (afluorescent material or a phosphorescent material), specific examples ofthe organic compounds are shown below though some of them overlap thespecific examples shown above.

In the case where the light-emitting substance is a fluorescentmaterial, examples of the organic compound (the host material) that canbe used in combination with the light-emitting substance includecondensed polycyclic aromatic compounds, such as an anthracenederivative, a tetracene derivative, a phenanthrene derivative, a pyrenederivative, a chrysene derivative, and a dibenzo[g,p]chrysenederivative. Furthermore, it is preferable to use the organic compounddescribed in Embodiment 1, which is one embodiment of the presentinvention.

Specific examples of the organic compound (the host material) used incombination with the fluorescent substance include9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation:PCzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole(abbreviation: DPCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole(abbreviation: PCPN), 9,10-diphenylanthracene (abbreviation: DPAnth),N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine(abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine(abbreviation: DPhPA), YGAPA, PCAPA,N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine(abbreviation: PCAPBA),N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA), 6,12-dimethoxy-5,11-diphenylchrysene,N,N,N,N,N′,N′,N′″,N′″-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine(abbreviation: DBC1), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole(abbreviation: CzPA),7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole(abbreviation: cgDBCzPA),6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan(abbreviation: 2mBnfPPA),9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)-biphenyl-4′-yl}-anthracene(abbreviation: FLPPA), 9,10-bis(3,5-diphenylphenyl)anthracene(abbreviation: DPPA), 9,10-di(2-naphthyl)anthracene (abbreviation: DNA),2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA),9,9′-bianthryl (abbreviation: BANT),9,9′-(stilbene-3,3′-diyl)diphenanthrene (abbreviation:DPNS),9,9′-(stilbene-4,4′-diyl)diphenanthrene (abbreviation: DPNS2),1,3,5-tri(1-pyrenyl)benzene (abbreviation: TPB3),5,12-diphenyltetracene, and 5,12-bis(biphenyl-2-yl)tetracene.

In the case where the light-emitting substance is a phosphorescentmaterial, an organic compound having triplet excitation energy (energydifference between a ground state and a triplet excited state) which ishigher than that of the light-emitting substance is preferably selectedas the organic compound (the host material) used in combination with thelight-emitting substance. In particular, the organic compound describedin Embodiment 1, which is one embodiment of the present invention, issuitable. Note that in the case where a plurality of organic compounds(e.g., a first host material and a second host material (or an assistmaterial)) are used in combination with a light-emitting substance inorder to form an exciplex, the plurality of organic compounds arepreferably mixed with a phosphorescent material.

Such a structure makes it possible to efficiently obtain light emissionutilizing ExTET (Exciplex-Triplet Energy Transfer), which is energytransfer from an exciplex to a light-emitting substance. Note that acombination of the plurality of organic compounds that easily forms anexciplex is preferably employed, and it is particularly preferable tocombine a compound that easily accepts holes (hole-transport material)and a compound that easily accepts electrons (electron-transportmaterial). The organic compound of one embodiment of the presentinvention described in Embodiment 1 has a stable triplet excited stateand thus is suitable for a host material in the case where thelight-emitting substance is a phosphorescent material. In the case wherean exciplex as described above is formed, the organic compound issuitable as the electron-transport material. Owing to its tripletexcitation energy level, the organic compound is particularly suitablewhen used in combination with a phosphorescent material that emits greenlight.

In the case where the light-emitting substance is a phosphorescentmaterial, examples of the organic compound (host material or assistmaterial) that can be used in combination with the light-emittingsubstance include an aromatic amine, a carbazole derivative, adibenzothiophene derivative, a dibenzofuran derivative, a zinc- oraluminum-based metal complex, an oxadiazole derivative, a triazolederivative, a benzimidazole derivative, a quinoxaline derivative, adibenzoquinoxaline derivative, a pyrimidine derivative, a triazinederivative, a pyridine derivative, a bipyridine derivative, and aphenanthroline derivative.

Among the above-described compounds, the same compounds as those givenabove as specific examples of the hole-transport material are given asspecific examples of the aromatic amine (a compound having an aromaticamine skeleton), which is an organic compound having a highhole-transport property.

Moreover, the same compounds as those given above as specific examplesof the hole-transport material are given as specific examples of thecarbazole derivative, which is an organic compound having a highhole-transport property.

Specific examples of the dibenzothiophene derivative and thedibenzofuran derivative, which are organic compounds having a highhole-transport property, include4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran(abbreviation: mmDBFFLBi-II),4,4′,4″-(benzene-1,3,5-triyl)tri(dibenzofuran) (abbreviation: DBF3P-II),1,3,5-tri(dibenzothiophen-4-yl)benzene (abbreviation: DBT3P-II),2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene(abbreviation: DBTFLP-III),4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene(abbreviation: DBTFLP-IV), and4-[3-(triphenylen-2-yl)phenyl]dibenzothiophene (abbreviation:mDBTPTp-II).

Specific examples of zinc- and aluminum-based metal complexes, which areorganic compounds having a high electron-transport property, includemetal complexes having a quinoline skeleton or a benzoquinolineskeleton, such as tris(8-quinolinolato)aluminum(III) (abbreviation:Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq₃),bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq₂),bis(2-methyl-8-quinolinolato) (4-phenylphenolato)aluminum(III)(abbreviation: BAlq), and bis(8-quinolinolato)zinc(II) (abbreviation:Znq).

Alternatively, a metal complex having an oxazole-based or thiazole-basedligand, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation:ZnPBO) or bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation:ZnBTZ), or the like can also be used.

Specific examples of the oxadiazole derivative, the triazole derivative,the benzimidazole derivative, the benzimidazole derivative, thequinoxaline derivative, the dibenzoquinoxaline derivative, and thephenanthroline derivative, which are organic compounds having a highelectron-transport property, include2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation:OXD-7),9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole(abbreviation:CO11),3-(4-biphenylyl)-5-(4-tert-butylphenyl)-4-phenyl-1,2,4-triazole(abbreviation: TAZ),2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole)(abbreviation: TPBI),2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole(abbreviation: mDBTBIm-II), 4,4′-bis(5-methylbenzoxazol-2-yl)stilbene(abbreviation: BzOS), bathophenanthroline (abbreviation: Bphen),bathocuproine (abbreviation: BCP),2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation:NBphen), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline(abbreviation: 2mDBTPDBq-II),2-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline(abbreviation:2mDBTBPDBq-II),2-[3′-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline(abbreviation:2mCzBPDBq),2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline(abbreviation: 2CzPDBq-III),7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation:7mDBTPDBq-II), and6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline(abbreviation:6mDBTPDBq-II).

Specific examples of a heterocyclic compound having a diazine skeleton,a heterocyclic compound having a triazine skeleton, and a heterocycliccompound having a pyridine skeleton, which are organic compounds havinga high electron-transport property, include4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation:4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine(abbreviation: 4,6mDBTP2Pm-II),4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation:4,6mCzP2Pm),2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine(abbreviation: PCCzPTzn),9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9′-phenyl-2,3′-bi-9H-carbazole(abbreviation: mPCCzPTzn-02),3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy),and 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB).Furthermore, in particular, the organic compound described in Embodiment1, which is one embodiment of the present invention, can also be used.

Furthermore, a high molecular compound such as poly(2,5-pyridinediyl)(abbreviation: PPy),poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)](abbreviation: PF-Py), orpoly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2′-bipyridine-6,6′-diyl)](abbreviation: PF-BPy) can be used as an organic compound having a highelectron-transport property.

In the case where a plurality of organic compounds are used in thelight-emitting layers (113, 113 a, 113 b, and 113 c), two kinds ofcompounds that form an exciplex (a first compound and a second compound)and an organometallic complex may be mixed and used. In that case,various organic compounds can be combined appropriately to be used; toform an exciplex efficiently, it is particularly preferable to combine acompound that easily accepts holes (hole-transport material) and acompound that easily accepts electrons (electron-transport material).Note that, as specific examples of the hole-transport material and theelectron-transport material, the materials described in this embodimentcan be used. With the structure, high efficiency, low voltage, and along lifetime can be achieved at the same time.

The TADF material refers to a material that can up-convert a tripletexcited state into a singlet excited state (i.e., reverse intersystemcrossing) using a little thermal energy and efficiently exhibits lightemission (fluorescence) from the singlet excited state. As the conditionunder which the thermally activated delayed fluorescence is efficientlyobtained, energy difference between the triplet excited level and thesinglet excited level being greater than or equal to 0 eV and less thanor equal to 0.2 eV, preferably greater than or equal to 0 eV and lessthan or equal to 0.1 eV can be given. Note that delayed fluorescenceexhibited by the TADF material refers to light emission having aspectrum similar to that of normal fluorescence and an extremely longlifetime. The lifetime is 10⁻⁶ seconds or longer, preferably 10⁻³seconds or longer.

Examples of the TADF material include fullerene, a derivative thereof,an acridine derivative such as proflavine, and eosin. In addition, ametal-containing porphyrin containing magnesium (Mg), zinc (Zn), cadmium(Cd), tin (Sn), platinum (Pt), indium (In), palladium (Pd), or the likecan be given. Examples of the metal-containing porphyrin include aprotoporphyrin-tin fluoride complex (abbreviation: SnF₂(Proto IX)), amesoporphyrin-tin fluoride complex (abbreviation: SnF₂(Meso IX)), ahematoporphyrin-tin fluoride complex (abbreviation: SnF₂(Hemato IX)), acoproporphyrin tetramethyl ester-tin fluoride complex (abbreviation:SnF₂(Copro III-4Me)), an octaethylporphyrin-tin fluoride complex(abbreviation: SnF₂(OEP)), an etioporphyrin-tin fluoride complex(abbreviation: SnF₂(Etio I)), and an octaethylporphyrin-platinumchloride complex (abbreviation: PtCl₂OEP).

Other than these, a heterocyclic compound having a π-electron richheteroaromatic ring and a π-electron deficient heteroaromatic ring, suchas2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine(abbreviation: PIC-TRZ),2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine(abbreviation: PCCzPTzn),2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine(abbreviation: PXZ-TRZ),3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole(abbreviation: PPZ-3TPT),3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation:ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone(abbreviation: DMAC-DPS), or10-phenyl-10H,10′H-spiro[acridin-9,9′-anthracen]-10′-one (abbreviation:ACRSA) can be used. Note that a substance in which the π-electron richheteroaromatic ring is directly bonded to the π-electron deficientheteroaromatic ring is particularly preferable because both the donorproperty of the π-electron rich heteroaromatic ring and the acceptorproperty of the π-electron deficient heteroaromatic ring are increasedand the energy difference between the singlet excited state and thetriplet excited state becomes small.

Note that when a TADF material is used, the TADF material can also beused in combination with another organic compound. In particular, theTADF material can be combined with the host materials, thehole-transport materials, and the electron-transport materials describedabove, and the organic compound of one embodiment of the presentinvention described in Embodiment 1 is preferably used as a hostmaterial for the TADF material.

Furthermore, when the above materials are used in combination with a lowmolecular material or a high molecular material, the above materials canbe used to form the light-emitting layers (113, 113 a, 113 b, and 113c). For the deposition, a known method (an evaporation method, a coatingmethod, a printing method, or the like) can be used as appropriate.

In the light-emitting element illustrated in FIG. 1, anelectron-transport layer (114 or 114 a) is formed over thelight-emitting layer (113 or 113 a) of the EL layer (103 or 103 a). Notethat in the case of the light-emitting element with the tandem structureillustrated in FIG. 1(D), after the EL layer 103 a and thecharge-generation layer 104 are formed, an electron-transport layer 114b is also formed over the light-emitting layer 113 b of the EL layer 103b.

<Electron-Transport Layer>

The electron-transport layers (114, 114 a, and 114 b) are each a layerthat transports the electrons, which are injected from the secondelectrode 102 by the electron-injection layers (115, 115 a, and 115 b),to the light-emitting layers (113, 113 a, and 113 b). Note that theelectron-transport layers (114, 114 a, and 114 b) are each a layercontaining an electron-transport material. It is preferable that theelectron-transport materials used in the electron-transport layers (114,114 a, and 114 b) be substances with an electron mobility of higher thanor equal to 1×10⁻⁶ cm²/Vs. Note that other substances can be used aslong as the substances have an electron-transport property higher than ahole-transport property. The organic compound of one embodiment of thepresent invention described in Embodiment 1 has an excellentelectron-transport property and thus can also be used for anelectron-transport layer.

As the electron-transport material, it is possible to use a materialhaving a high electron-transport property, such as a metal complexhaving a quinoline skeleton, a metal complex having a benzoquinolineskeleton, a metal complex having an oxazole skeleton, a metal complexhaving a thiazole skeleton, an oxadiazole derivative, a triazolederivative, an imidazole derivative, an oxazole derivative, a thiazolederivative, a phenanthroline derivative, a quinoline derivative having aquinoline ligand, a benzoquinoline derivative, a quinoxaline derivative,a dibenzoquinoxaline derivative, a pyridine derivative, a bipyridinederivative, a pyrimidine derivative, or a π-electron deficientheteroaromatic compound such as a nitrogen-containing heteroaromaticcompound.

Specific examples of the electron-transport material include metalcomplexes having a quinoline skeleton or a benzoquinoline skeleton, suchas tris(8-quinolinolato)aluminum(III) (abbreviation: Alq₃),tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq₃),bis(10-hydroxybenzo[h]quinolinato)beryllium(II) (abbreviation: BeBq₂),bis(2-methyl-8-quinolinolato) (4-phenylphenolato)aluminum(III)(abbreviation: BAlq), and bis(8-quinolinolato)zinc(II) (abbreviation:Znq), and metal complexes having an oxazole skeleton or a thiazoleskeleton, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II)(abbreviation: ZnPBO), bis[2-(2-benzothiazolyl)phenolato]zinc(II)(abbreviation: ZnBTZ), andbis[2-(2-hydroxyphenyl)benzothiazolato]zinc(II) (abbreviation:Zn(BTZ)₂).

Other than metal complexes, any of the following can also be used: anoxadiazole derivative such as2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation:PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(abbreviation: OXD-7), and9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation:CO11); a triazole derivative such as3-(4-biphenylyl)-5-(4-tert-butylphenyl)-4-phenyl-1,2,4-triazole(abbreviation: TAZ) and3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole(abbreviation: p-EtTAZ); an imidazole derivative (including abenzimidazole derivative) such as2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole)(abbreviation: TPBI) and2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole(abbreviation: mDBTBIm-II); an oxazole derivative such as4,4′-bis(5-methylbenzoxazol-2-yl)stilbene (abbreviation: BzOS); aphenanthroline derivative such as bathophenanthroline (abbreviation:Bphen), bathocuproine (abbreviation: BCP), and2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation:NBphen); a quinoxaline derivative or a dibenzoquinoxaline derivativesuch as 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline(abbreviation: 2mDBTPDBq-II),2-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline(abbreviation:2mDBTBPDBq-II),2-[3′-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline(abbreviation:2mCzBPDBq),2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline(abbreviation: 2CzPDBq-III),7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation:7mDBTPDBq-II), and6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation:6mDBTPDBq-II); a pyridine derivative such as3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) and1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB); apyrimidine derivative such as4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation:4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine(abbreviation: 4,6mDBTP2Pm-II), and4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation:4,6mCzP2Pm); and a triazine derivative such as2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine(abbreviation: PCCzPTzn). Furthermore, in particular, the organiccompound described in Embodiment 1, which is one embodiment of thepresent invention, can also be used.

Furthermore, a high molecular compound such as poly(2,5-pyridinediyl)(abbreviation: PPy),poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)](abbreviation: PF-Py), orpoly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2′-bipyridine-6,6′-diyl)](abbreviation: PF-BPy) can also be used.

Each of the electron-transport layers (114, 114 a, and 114 b) is notlimited to a single layer, and may be a stack of two or more layers eachmade of any of the above substances.

In the light-emitting element illustrated in FIG. 1(D), theelectron-injection layer 115 a is formed over the electron-transportlayer 114 a of the EL layer 103 a by a vacuum evaporation method.Subsequently, the EL layer 103 a and the charge-generation layer 104 areformed, the components up to the electron-transport layer 114 b of theEL layer 103 b are formed, and then the electron-injection layer 115 bis formed thereover by a vacuum evaporation method.

<Electron-Injection Layer>

The electron-injection layers (115, 115 a, and 115 b) are each a layercontaining a substance having a high electron-injection property. Theelectron-injection layers (115, 115 a, and 115 b) can each be formedusing an alkali metal, an alkaline earth metal, or a compound thereof,such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride(CaF₂), or lithium oxide (LiO_(x)). A rare earth metal compound such aserbium fluoride (ErF₃) can be used. Electride may also be used for theelectron-injection layers (115, 115 a, and 115 b). Examples of theelectride include a substance in which electrons are added at highconcentration to a mixed oxide of calcium and aluminum. Note that any ofthe substances used in the electron-transport layers (114, 114 a, and114 b), which are given above, can also be used.

A composite material in which an organic compound and an electron donor(donor) are mixed may also be used in the electron-injection layers(115, 115 a, and 115 b). Such a composite material is excellent in anelectron-injection property and an electron-transport property becauseelectrons are generated in the organic compound by the electron donor.In this case, the organic compound is preferably a material excellent intransporting the generated electrons; specifically, for example, theabove-mentioned electron-transport materials (metal complexes,heteroaromatic compounds, and the like) used in the electron-transportlayers (114, 114 a, and 114 b) can be used. Any substance showing anelectron-donating property with respect to the organic compound canserve as an electron donor. Specifically, an alkali metal, an alkalineearth metal, and a rare earth metal are preferable, and lithium, cesium,magnesium, calcium, erbium, ytterbium, and the like are given. Inaddition, an alkali metal oxide and an alkaline earth metal oxide arepreferable, and lithium oxide, calcium oxide, barium oxide, and the likeare given. A Lewis base such as magnesium oxide can also be used. Anorganic compound such as tetrathiafulvalene (abbreviation: TTF) can alsobe used.

Note that in the case where light obtained from the light-emitting layer113 b is amplified in the light-emitting element illustrated in FIG.1(D), the optical path length between the second electrode 102 and thelight-emitting layer 113 b is preferably less than one fourth of thewavelength λ of light emitted from the light-emitting layer 113 b. Inthat case, the optical path length can be adjusted by changing thethickness of the electron-transport layer 114 b or theelectron-injection layer 115 b.

<Charge-Generation Layer>

In the light-emitting element illustrated in FIG. 1(D), thecharge-generation layer 104 has a function of injecting electrons intothe EL layer 103 a and injecting holes into the EL layer 103 b whenvoltage is applied between the first electrode (anode) 101 and thesecond electrode (cathode) 102. Note that the charge-generation layer104 may have either a structure in which an electron acceptor (acceptor)is added to a hole-transport material or a structure in which anelectron donor (donor) is added to an electron-transport material.Alternatively, both of these structures may be stacked. Note thatforming the charge-generation layer 104 with the use of any of the abovematerials can suppress an increase in drive voltage in the case wherethe EL layers are stacked.

In the case where the charge-generation layer 104 has a structure inwhich an electron acceptor is added to a hole-transport material, any ofthe materials described in this embodiment can be used as thehole-transport material. As the electron acceptor,7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation:F₄-TCNQ), chloranil, and the like can be given. In addition, oxides ofmetals that belong to Group 4 to Group 8 of the periodic table can begiven. Specifically, vanadium oxide, niobium oxide, tantalum oxide,chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide,rhenium oxide, and the like can be given.

In the case where the charge-generation layer 104 has a structure inwhich an electron donor is added to an electron-transport material, anyof the materials described in this embodiment can be used as theelectron-transport material. As the electron donor, it is possible touse an alkali metal, an alkaline earth metal, a rare earth metal, metalsthat belong to Groups 2 and 13 of the periodic table, or an oxide orcarbonate thereof. Specifically, lithium (Li), cesium (Cs), magnesium(Mg), calcium (Ca), ytterbium (Yb), indium (In), lithium oxide, cesiumcarbonate, or the like is preferably used. Alternatively, an organiccompound such as tetrathianaphthacene may be used as the electron donor.

Note that the EL layer 103 c in FIG. 1(E) has a structure similar tothose of the above-described EL layers (103, 103 a, and 103 b). Inaddition, the charge-generation layers 104 a and 104 b each have astructure similar to that of the above-described charge-generation layer104.

<Substrate>

The light-emitting element described in this embodiment can be formedover any of a variety of substrates. Note that the type of the substrateis not limited to a certain type. Examples of the substrate includesemiconductor substrates (e.g., a single crystal substrate and a siliconsubstrate), an SOI substrate, a glass substrate, a quartz substrate, aplastic substrate, a metal substrate, a stainless steel substrate, asubstrate including stainless steel foil, a tungsten substrate, asubstrate including tungsten foil, a flexible substrate, a laminatefilm, paper including a fibrous material, and a base material film.

Note that examples of the glass substrate include barium borosilicateglass, aluminoborosilicate glass, and soda lime glass. Examples of theflexible substrate, the laminate film, and the base material filminclude plastics typified by polyethylene terephthalate (PET),polyethylene naphthalate (PEN), and polyether sulfone (PES); a syntheticresin such as an acrylic resin; polypropylene; polyester; polyvinylfluoride; polyvinyl chloride; polyamide; polyimide; an aramid resin; anepoxy resin; an inorganic vapor deposition film; and paper.

Note that for fabrication of the light-emitting element described inthis embodiment, a vacuum process such as an evaporation method or asolution process such as a spin coating method or an ink-jet method canbe used. In the case where an evaporation method is used, a physicalvapor deposition method (PVD method) such as a sputtering method, an ionplating method, an ion beam evaporation method, a molecular beamevaporation method, or a vacuum evaporation method; a chemical vapordeposition method (CVD method); or the like can be used. Specifically,the functional layers (the hole-injection layers (111, 111 a, and 111b), the hole-transport layers (112, 112 a, and 112 b), thelight-emitting layers (113, 113 a, 113 b, and 113 c), theelectron-transport layers (114, 114 a, and 114 b), and theelectron-injection layers (115, 115 a, and 115 b)) included in the ELlayers and the charge-generation layers (104, 104 a, and 104 b) of thelight-emitting element can be formed by an evaporation method (e.g., avacuum evaporation method), a coating method (e.g., a dip coatingmethod, a die coating method, a bar coating method, a spin coatingmethod, or a spray coating method), a printing method (e.g., an ink-jetmethod, a screen printing (stencil) method, an offset printing(planography) method, a flexography (relief printing) method, a gravureprinting method, a micro-contact printing method, or a nanoinprintingmethod), or the like.

Note that materials that can be used for the functional layers (thehole-injection layers (111, 111 a, and 111 b), the hole-transport layers(112, 112 a, and 112 b), the light-emitting layers (113, 113 a, 113 b,and 113 c), the electron-transport layers (114, 114 a, and 114 b), andthe electron-injection layers (115, 115 a, and 115 b)) included in theEL layers (103, 103 a, and 103 b) and the charge-generation layers (104,104 a, and 104 b) of the light-emitting element described in thisembodiment are not limited to the above materials, and other materialscan also be used in combination as long as the functions of the layersare fulfilled. For example, a high molecular compound (e.g., anoligomer, a dendrimer, and a polymer), a middle molecular compound (acompound between a low molecular compound and a high molecular compoundwith a molecular weight of 400 to 4000), or an inorganic compound (e.g.,a quantum dot material) can be used. Note that as the quantum dotmaterial, a colloidal quantum dot material, an alloyed quantum dotmaterial, a core-shell quantum dot material, a core quantum dotmaterial, or the like can be used.

The structure described in this embodiment can be used in an appropriatecombination with any of the structures described in the otherembodiments.

Embodiment 3

In this embodiment, a light-emitting device of one embodiment of thepresent invention will be described. Note that a light-emitting deviceillustrated in FIG. 2(A) is an active-matrix light-emitting device inwhich transistors (FETs) 202 over a first substrate 201 are electricallyconnected to light-emitting elements (203R, 203G, 203B, and 203W); thelight-emitting elements (203R, 203G, 203B, and 203W) include a common ELlayer 204 and each have a microcavity structure in which the opticalpath length between electrodes of each light-emitting element isadjusted according to the emission color of the light-emitting element.In addition, the light-emitting device is a top-emission light-emittingdevice in which light is emitted from the EL layer 204 through colorfilters (206R, 206G, and 206B) formed on a second substrate 205.

In the light-emitting device illustrated in FIG. 2(A), the firstelectrode 207 is formed so as to function as a reflective electrode. Thesecond electrode 208 is formed so as to function as a semi-transmissiveand semi-reflective electrode. Note that description in any of the otherembodiments can be referred to for electrode materials forming the firstelectrode 207 and the second electrode 208 and appropriate materials canbe used.

In the case where the light-emitting element 203R is ared-light-emitting element, the light-emitting element 203G is agreen-light-emitting element, the light-emitting element 203B is ablue-light-emitting element, and the light-emitting element 203W is awhite-light-emitting element in FIG. 2(A), for example, a gap betweenthe first electrode 207 and the second electrode 208 in thelight-emitting element 203R is adjusted to have an optical path length200R, a gap between the first electrode 207 and the second electrode 208in the light-emitting element 203G is adjusted to have an optical pathlength 200G, and a gap between the first electrode 207 and the secondelectrode 208 in the light-emitting element 203B is adjusted to have anoptical path length 200B as illustrated in FIG. 2(B). Note that opticaladjustment can be performed in such a manner that a conductive layer210R is stacked over the first electrode 207 in the light-emittingelement 203R and a conductive layer 210G is stacked over the firstelectrode 207 in the light-emitting element 203G as illustrated in FIG.2(B).

The color filters (206R, 206G, and 206B) are formed on the secondsubstrate 205. Note that the color filters each transmit visible lightin a specific wavelength range and blocks visible light in a specificwavelength range. Thus, as illustrated in FIG. 2(A), the color filter206R that transmits only light in the red wavelength range is providedin a position overlapping with the light-emitting element 203R, wherebyred light emission can be obtained from the light-emitting element 203R.The color filter 206G that transmits only light in the green wavelengthrange is provided in a position overlapping with the light-emittingelement 203G, whereby green light emission can be obtained from thelight-emitting element 203G. The color filter 206B that transmits onlylight in the blue wavelength range is provided in a position overlappingwith the light-emitting element 203B, whereby blue light emission can beobtained from the light-emitting element 203B. Note that thelight-emitting element 203W can emit white light without a color filter.Note that a black layer (black matrix) 209 may be provided at an endportion of one type of color filter. The color filters (206R, 206G, and206B) and the black layer 209 may be covered with an overcoat layerusing a transparent material.

Although the light-emitting device illustrated in FIG. 2(A) has astructure in which light is extracted from the second substrate 205 side(top emission structure), the light-emitting device may have a structurein which light is extracted from the first substrate 201 side where theFETs 202 are formed (bottom emission structure) as illustrated in FIG.2(C). For a bottom-emission light-emitting device, the first electrode207 is formed so as to function as a semi-transmissive andsemi-reflective electrode and the second electrode 208 is formed so asto function as a reflective electrode. As the first substrate 201, asubstrate having at least a light-transmitting property is used. Asillustrated in FIG. 2(C), color filters (206R′, 206G′, and 206B′) areprovided closer to the first substrate 201 than the light-emittingelements (203R, 203G, and 203B) are.

FIG. 2(A) illustrates the case where the light-emitting elements are thered-light-emitting element, the green-light-emitting element, theblue-light-emitting element, and the white-light-emitting element;however, the light-emitting elements of embodiments of the presentinvention are not limited to the above structures, and ayellow-light-emitting element or an orange-light-emitting element may beincluded. Note that description in any of the other embodiments can bereferred to for materials that are used for the EL layers (alight-emitting layer, a hole-injection layer, a hole-transport layer, anelectron-transport layer, an electron-injection layer, acharge-generation layer, and the like) to fabricate each of thelight-emitting elements and appropriate materials can be used. In thatcase, a color filter needs to be appropriately selected according to theemission color of the light-emitting element.

With the above structure, a light-emitting device includinglight-emitting elements that exhibit a plurality of emission colors canbe obtained.

Note that the structures described in this embodiment can be used in anappropriate combination with any of the structures described in theother embodiments.

Embodiment 4

In this embodiment, a light-emitting device of one embodiment of thepresent invention will be described.

The use of the element structure of the light-emitting element of oneembodiment of the present invention allows fabrication of anactive-matrix light-emitting device or a passive-matrix light-emittingdevice. Note that an active-matrix light-emitting device has a structureincluding a combination of a light-emitting element and a transistor(FET). Thus, each of a passive-matrix light-emitting device and anactive-matrix light-emitting device is included in one embodiment of thepresent invention. Note that any of the light-emitting elementsdescribed in the other embodiments can be used in the light-emittingdevice described in this embodiment.

In this embodiment, an active-matrix light-emitting device will bedescribed with reference to FIG. 3.

FIG. 3(A) is a top view illustrating a light-emitting device, and FIG.3(B) is a cross-sectional view taken along a chain line A-A′ in FIG.3(A). The active-matrix light-emitting device includes a pixel portion302, a driver circuit portion (source line driver circuit) 303, anddriver circuit portions (gate line driver circuits) (304 a and 304 b)that are provided over a first substrate 301. The pixel portion 302 andthe driver circuit portions (303, 304 a, and 304 b) are sealed betweenthe first substrate 301 and a second substrate 306 with a sealant 305.

A lead wiring 307 is provided over the first substrate 301. The leadwiring 307 is electrically connected to an FPC 308 which is an externalinput terminal. Note that the FPC 308 transmits a signal (e.g., a videosignal, a clock signal, a start signal, or a reset signal) or apotential from the outside to the driver circuit portions (303, 304 a,and 304 b). The FPC 308 may be provided with a printed wiring board(PWB). Note that the light-emitting device provided with an FPC or a PWBis included in the category of a light-emitting device.

Next, FIG. 3(B) illustrates the cross-sectional structure.

The pixel portion 302 is made up of a plurality of pixels each of whichincludes an FET (switching FET) 311, an FET (current control FET) 312,and a first electrode 313 electrically connected to the FET 312. Notethat the number of FETs included in each pixel is not particularlylimited and can be set appropriately as needed.

As FETs 309, 310, 311, and 312, for example, a staggered transistor oran inverted staggered transistor can be used without particularlimitation. A top-gate transistor, a bottom-gate transistor, or the likemay be used.

Note that there is no particular limitation on the crystallinity of asemiconductor that can be used for the FETs 309, 310, 311, and 312, andan amorphous semiconductor or a semiconductor having crystallinity (amicrocrystalline semiconductor, a polycrystalline semiconductor, asingle crystal semiconductor, or a semiconductor partly includingcrystal regions) may be used. The use of a semiconductor havingcrystallinity can suppress deterioration of the transistorcharacteristics, which is preferable.

For these semiconductors, a Group 14 element, a compound semiconductor,an oxide semiconductor, an organic semiconductor, or the like can beused, for example. Typically, a semiconductor containing silicon, asemiconductor containing gallium arsenide, an oxide semiconductorcontaining indium, or the like can be used.

The driver circuit portion 303 includes the FET 309 and the FET 310. TheFET 309 and the FET 310 may be formed with a circuit includingtransistors having the same conductivity type (either n-channeltransistors or p-channel transistors) or a CMOS circuit including ann-channel transistor and a p-channel transistor. Furthermore, astructure including a driver circuit outside may be employed.

An end portion of the first electrode 313 is covered with an insulator314. For the insulator 314, an organic compound such as a negativephotosensitive resin or a positive photosensitive resin (acrylic resin),or an inorganic compound such as silicon oxide, silicon oxynitride, orsilicon nitride can be used. An upper end portion or a lower end portionof the insulator 314 preferably has a curved surface with curvature. Inthat case, favorable coverage with a film formed over the insulator 314can be obtained.

An EL layer 315 and a second electrode 316 are stacked over the firstelectrode 313. The EL layer 315 includes a light-emitting layer, ahole-injection layer, a hole-transport layer, an electron-transportlayer, an electron-injection layer, a charge-generation layer, and thelike.

The structure and materials described in any of the other embodimentscan be used for the structure of a light-emitting element 317 describedin this embodiment. Although not illustrated here, the second electrode316 is electrically connected to the FPC 308 which is an external inputterminal.

Although the cross-sectional view illustrated in FIG. 3(B) illustratesonly one light-emitting element 317, a plurality of light-emittingelements are arranged in a matrix in the pixel portion 302.Light-emitting elements from which light of three kinds of colors (R, G,and B) are obtained are selectively formed in the pixel portion 302,whereby a light-emitting device capable of full-color display can beformed. In addition to the light-emitting elements from which light ofthree kinds of colors (R, G, and B) are obtained, for example,light-emitting elements from which light of white (W), yellow (Y),magenta (M), cyan (C), and the like are obtained may be formed. Forexample, the light-emitting elements from which light of some of theabove colors are obtained are added to the light-emitting elements fromwhich light of three kinds of colors (R, G, and B) are obtained, wherebyeffects such as an improvement in color purity and a reduction in powerconsumption can be obtained. Alternatively, a light-emitting device thatis capable of full-color display may be fabricated by a combination withcolor filters. As the kinds of color filters, red (R), green (G), blue(B), cyan (C), magenta (M), and yellow (Y) color filters and the likecan be used.

When the second substrate 306 and the first substrate 301 are bonded toeach other with the sealant 305, the FETs (309, 310, 311, and 312) andthe light-emitting element 317 over the first substrate 301 are providedin a space 318 surrounded by the first substrate 301, the secondsubstrate 306, and the sealant 305. Note that the space 318 may befilled with an inert gas (e.g., nitrogen or argon) or an organicsubstance (including the sealant 305).

An epoxy resin or glass frit can be used for the sealant 305. It ispreferable to use a material that is permeable to as little moisture andoxygen as possible for the sealant 305. As the second substrate 306, amaterial that can be used as the first substrate 301 can be similarlyused. Thus, any of the various substrates described in the otherembodiments can be appropriately used. As the substrate, a glasssubstrate, a quartz substrate, or a plastic substrate made of FRP(Fiber-Reinforced Plastics), PVF (polyvinyl fluoride), polyester, anacrylic resin, or the like can be used. In the case where glass frit isused for the sealant, the first substrate 301 and the second substrate306 are preferably glass substrates in terms of adhesion.

In the above manner, the active-matrix light-emitting device can beobtained.

In the case where the active-matrix light-emitting device is formed overa flexible substrate, the FETs and the light-emitting element may bedirectly formed over the flexible substrate; alternatively, the FETs andthe light-emitting element may be formed over a substrate provided witha separation layer and then separated at the separation layer byapplication of heat, force, laser irradiation, or the like to betransferred to a flexible substrate. For the separation layer, a stackincluding inorganic films such as a tungsten film and a silicon oxidefilm, or an organic resin film of polyimide or the like can be used, forexample. Examples of the flexible substrate include, in addition to asubstrate over which a transistor can be formed, a paper substrate, acellophane substrate, an aramid film substrate, a polyimide filmsubstrate, a cloth substrate (including a natural fiber (e.g., silk,cotton, or hemp), a synthetic fiber (e.g., nylon, polyurethane, orpolyester), a regenerated fiber (e.g., acetate, cupro, rayon, orregenerated polyester), or the like), a leather substrate, and a rubbersubstrate. With the use of any of these substrates, high durability,high heat resistance, a reduction in weight, and a reduction inthickness can be achieved.

Note that the structures described in this embodiment can be used in anappropriate combination with the structures described in the otherembodiments.

Embodiment 5

In this embodiment, examples of a variety of electronic devices and anautomobile completed using the light-emitting element of one embodimentof the present invention or a light-emitting device including thelight-emitting element of one embodiment of the present invention aredescribed. Note that the light-emitting device can be used mainly in adisplay portion of the electronic device described in this embodiment.

Electronic devices illustrated in FIG. 4(A) to FIG. 4(C) can include ahousing 7000, a display portion 7001, a speaker 7003, an LED lamp 7004,operation keys 7005 (including a power switch or an operation switch), aconnection terminal 7006, a sensor 7007 (a sensor having a function ofmeasuring force, displacement, position, speed, acceleration, angularvelocity, rotational frequency, distance, light, liquid, magnetism,temperature, chemical substance, sound, time, hardness, electric field,current, voltage, electric power, radiation, flow rate, humidity,gradient, oscillation, odor, or infrared ray), a microphone 7008, andthe like.

FIG. 4(A) is a mobile computer which can include a switch 7009, aninfrared port 7010, and the like in addition to the above components.

FIG. 4(B) is a portable image reproducing device (e.g., a DVD player)which is provided with a recording medium and can include a seconddisplay portion 7002, a recording medium reading portion 7011, and thelike in addition to the above components.

FIG. 4(C) is a digital camera with a television reception function,which can include an antenna 7014, a shutter button 7015, an imagereceiving portion 7016, and the like in addition to the abovecomponents.

FIG. 4(D) is a portable information terminal. The portable informationterminal has a function of displaying information on three or moresurfaces of the display portion 7001. Here, an example in whichinformation 7052, information 7053, and information 7054 are displayedon different surfaces is shown. For example, the user can check theinformation 7053 displayed in a position that can be observed from abovethe portable information terminal, with the portable informationterminal put in a breast pocket of his/her clothes. The user can see thedisplay without taking out the portable information terminal from thepocket and decide whether to answer the call, for example.

FIG. 4(E) is a portable information terminal (e.g., a smartphone) andcan include the display portion 7001, the operation key 7005, and thelike in the housing 7000. Note that the speaker 7003, the connectionterminal 7006, the sensor 7007, or the like may be provided in theportable information terminal. The portable information terminal candisplay characters and image information on its plurality of surfaces.Here, an example is shown in which three icons 7050 are displayed.Information 7051 indicated by dashed rectangles can be displayed onanother surface of the display portion 7001. Examples of the information7051 include notification of reception of an e-mail, SNS, or an incomingcall, the title and sender of an e-mail, SNS, or the like, the date, thetime, remaining battery, and the reception strength of an antenna.Alternatively, the icon 7050 or the like may be displayed in theposition where the information 7051 is displayed.

FIG. 4(F) is a large-size television set (also referred to as TV or atelevision receiver), which can include the housing 7000, the displayportion 7001, and the like. In addition, shown here is a structure wherethe housing 7000 is supported by a stand 7018. The television set can beoperated with a separate remote controller 7111 or the like. Note thatthe display portion 7001 may include a touch sensor, in which case thetelevision set may be operated by touch on the display portion 7001 witha finger or the like. The remote controller 7111 may be provided with adisplay portion for displaying data output from the remote controller7111. With operation keys or a touch panel provided in the remotecontroller 7111, channels and volume can be operated and imagesdisplayed on the display portion 7001 can be operated.

The electronic devices illustrated in FIG. 4(A) to FIG. 4(F) can have avariety of functions. For example, they can have a function ofdisplaying a variety of data (e.g., a still image, a moving image, and atext image) on the display portion, a touch panel function, a functionof displaying a calendar, date, time, or the like, a function ofcontrolling processing with a variety of software (programs), a wirelesscommunication function, a function of being connected to a variety ofcomputer networks with a wireless communication function, a function oftransmitting and receiving a variety of data with a wirelesscommunication function, and a function of reading out a program or datastored in a recording medium and displaying it on the display portion.Furthermore, the electronic device including a plurality of displayportions can have a function of displaying image data mainly on onedisplay portion while displaying text data mainly on the other displayportion, a function of displaying a three-dimensional image bydisplaying images on a plurality of display portions with a parallaxtaken into account, or the like. Furthermore, the electronic deviceincluding an image receiving portion can have a function of taking astill image, a function of taking a moving image, a function ofautomatically or manually correcting a taken image, a function ofstoring a taken image in a recording medium (an external recordingmedium or a recording medium incorporated in the camera), a function ofdisplaying a taken image on the display portion, or the like. Note thatfunctions that the electronic devices illustrated in FIG. 4(A) to FIG.4(F) can have are not limited to those, and the electronic devices canhave a variety of functions.

FIG. 4(G) is a watch-type portable information terminal, which can beused as a smart watch, for example. The watch-type portable informationterminal includes the housing 7000, the display portion 7001, operationbuttons 7022 and 7023, a connection terminal 7024, a band 7025, amicrophone 7026, a sensor 7029, a speaker 7030, and the like. Thedisplay surface of the display portion 7001 is bent, and display can beperformed on the bent display surface. Furthermore, mutual communicationbetween the portable information terminal and, for example, a headsetcapable of wireless communication can be performed, and thus hands-freecalling is possible with the portable information terminal. With theconnection terminal 7024, the portable information terminal can performmutual data transmission with another information terminal and charging.Wireless power feeding can also be employed for the charging operation.

The display portion 7001 mounted in the housing 7000 also serving as abezel includes a non-rectangular display region. The display portion7001 can display an icon indicating time, another icon, and the like.The display portion 7001 may be a touch panel (input/output device)including a touch sensor (input device).

Note that the smart watch illustrated in FIG. 4(G) can have a variety offunctions. For example, they can have a function of displaying a varietyof data (e.g., a still image, a moving image, and a text image) on thedisplay portion, a touch panel function, a function of displaying acalendar, date, time, or the like, a function of controlling processingwith a variety of software (programs), a wireless communicationfunction, a function of being connected to a variety of computernetworks with a wireless communication function, a function oftransmitting and receiving a variety of data with a wirelesscommunication function, and a function of reading out a program or datastored in a recording medium and displaying it on the display portion.

Moreover, a speaker, a sensor (a sensor having a function of measuringforce, displacement, position, speed, acceleration, angular velocity,rotational frequency, distance, light, liquid, magnetism, temperature,chemical substance, sound, time, hardness, electric field, current,voltage, electric power, radiation, flow rate, humidity, gradient,oscillation, odor, or infrared rays), a microphone, and the like can beincluded inside the housing 7000.

Note that the light-emitting device of one embodiment of the presentinvention and the display device including the light-emitting element ofone embodiment of the present invention can be used in the displayportions of the electronic devices described in this embodiment,enabling the electronic devices to have a long lifetime.

Another electronic device including the light-emitting device is afoldable portable information terminal illustrated in FIGS. 5(A) to5(C). FIG. 5(A) illustrates a portable information terminal 9310 whichis opened. FIG. 5(B) illustrates the portable information terminal 9310in a state in the middle of change from one of an opened state and afolded state to the other. FIG. 5(C) illustrates the portableinformation terminal 9310 which is folded. The portable informationterminal 9310 is excellent in portability when folded, and is excellentin display browsability when opened because of a seamless large displayregion.

A display portion 9311 is supported by three housings 9315 joinedtogether by hinges 9313. Note that the display portion 9311 may be atouch panel (input/output device) including a touch sensor (inputdevice). By bending the display portion 9311 at a portion between twohousings 9315 with the use of the hinges 9313, the portable informationterminal 9310 can be reversibly changed in shape from an opened state toa folded state. The light-emitting device of one embodiment of thepresent invention can be used for the display portion 9311. In addition,an electronic device having along lifetime can be provided. A displayregion 9312 in the display portion 9311 is a display region that ispositioned at a side surface of the portable information terminal 9310which is folded. On the display region 9312, information icons, fileshortcuts of frequently used applications or programs, and the like canbe displayed, and confirmation of information and start of anapplication can be smoothly performed.

FIGS. 6(A) and 6(B) illustrate an automobile including thelight-emitting device. In other words, the light-emitting device can beintegrated into an automobile. Specifically, the light-emitting devicecan be applied to lights 5101 (including lights of the rear part of thecar), a wheel 5102, a part or the whole of a door 5103, or the like onthe outer side of the automobile which is illustrated in FIG. 6(A). Thelight-emitting device can also be applied to a display portion 5104, asteering wheel 5105, a shifter 5106, a seat 5107, an inner rearviewmirror 5108, or the like on the inner side of the automobile which isillustrated in FIG. 6(B). Apart from that, the light-emitting device maybe used for a part of the glass window.

In the above manner, the electronic devices and automobiles in which thelight-emitting device or the display device of one embodiment of thepresent invention is used can be obtained. In that case, a long-lifetimeelectronic device can be obtained. Note that the light-emitting deviceor the display device can be used for electronic devices and automobilesin a variety of fields without being limited to those described in thisembodiment.

Note that the structures described in this embodiment can be used in anappropriate combination with any of the structures described in theother embodiments.

Embodiment 6

In this embodiment, the structure of a lighting device fabricated usingthe light-emitting device of one embodiment of the present invention orthe light-emitting element which is part of the light-emitting devicewill be described with reference to FIG. 7.

FIGS. 7(A) and 7(B) show examples of cross-sectional views of lightingdevices. FIG. 7(A) is a bottom-emission lighting device in which lightis extracted from the substrate side, and FIG. 7(B) is a top-emissionlighting device in which light is extracted from the sealing substrateside.

A lighting device 4000 illustrated in FIG. 7(A) includes alight-emitting element 4002 over a substrate 4001. In addition, thelighting device 4000 includes a substrate 4003 with unevenness on theoutside of the substrate 4001. The light-emitting element 4002 includesa first electrode 4004, an EL layer 4005, and a second electrode 4006.

The first electrode 4004 is electrically connected to an electrode 4007,and the second electrode 4006 is electrically connected to an electrode4008. In addition, an auxiliary wiring 4009 electrically connected tothe first electrode 4004 may be provided. Note that an insulating layer4010 is formed over the auxiliary wiring 4009.

The substrate 4001 and a sealing substrate 4011 are bonded to each otherwith a sealant 4012. A desiccant 4013 is preferably provided between thesealing substrate 4011 and the light-emitting element 4002. Thesubstrate 4003 has the unevenness illustrated in FIG. 7(A), whereby theextraction efficiency of light generated in the light-emitting element4002 can be increased.

A lighting device 4200 illustrated in FIG. 7(B) includes alight-emitting element 4202 over a substrate 4201. The light-emittingelement 4202 includes a first electrode 4204, an EL layer 4205, and asecond electrode 4206.

The first electrode 4204 is electrically connected to an electrode 4207,and the second electrode 4206 is electrically connected to an electrode4208. An auxiliary wiring 4209 electrically connected to the secondelectrode 4206 may also be provided. In addition, an insulating layer4210 may be provided under the auxiliary wiring 4209.

The substrate 4201 and a sealing substrate 4211 with unevenness arebonded to each other with a sealant 4212. A barrier film 4213 and aplanarization film 4214 may be provided between the sealing substrate4211 and the light-emitting element 4202. The sealing substrate 4211 hasthe unevenness illustrated in FIG. 7(B), whereby the extractionefficiency of light generated in the light-emitting element 4202 can beincreased.

Application examples of such lighting devices include a ceiling lightfor indoor lighting. Examples of the ceiling light include a ceilingdirect mount light and a ceiling embedded light. Such a lighting deviceis fabricated using the light-emitting device and a housing or a coverin combination.

For another example, such lighting devices can be used for a foot lightthat illuminates a floor so that safety on the floor can be improved.For example, the foot light can be effectively used in a bedroom, on astaircase, or on a passage. In that case, the size or shape of the footlight can be changed depending on the area or structure of a room. Thefoot light can be a stationary lighting device fabricated using thelight-emitting device and a support base in combination.

Such lighting devices can also be used for a sheet-like lighting device(sheet-like lighting). The sheet-like lighting, which is attached to awall when used, is space-saving and thus can be used for a wide varietyof uses. Furthermore, the area of the sheet-like lighting can be easilyincreased. The sheet-like lighting can also be used on a wall or housinghaving a curved surface.

Besides the above examples, the light-emitting device which is oneembodiment of the present invention or the light-emitting element whichis a part of the light-emitting device can be used as part of furniturein a room, so that a lighting device which has a function of thefurniture can be obtained.

As described above, a variety of lighting devices that include thelight-emitting device can be obtained. Note that these lighting devicesare also embodiments of the present invention.

The structures described in this embodiment can be used in anappropriate combination with the structures described in the otherembodiments.

Example 1 Synthesis Example 1

In this example, a synthesis method of4-[3-(dibenzothiophen-4-yl)phenyl]-8-phenyl-[1]benzofuro[3,2-d]pyrimidine(abbreviation: 8Ph-4mDBtPBfpm), which is an organic compound of oneembodiment of the present invention represented by Structural Formula(100) in Embodiment 1, will be described. Note that the structure of8Ph-4mDBtPBfpm is shown below.

Synthesis of4-[3-(dibenzothiophen-4-yl)phenyl]-8-phenyl-[1]benzofuro[3,2-d]pyrimidine

Into a three-neck flask, 3.00 g of8-chloro-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine,0.95 g of a phenylboronic acid, 4.12 g of tripotassium phosphate, 65 mLof diglyme, and 1.44 g of t-butanol were put, they were degassed bybeing stirred under reduced pressure, and the air in the flask wasreplaced with nitrogen. To this mixture, 42.7 mg of palladium(II)acetate and 140 mg of di(1-adamantyl)-n-butylphosphine were added,followed by stirring at 120° C. for 15.5 hours.

To this reaction liquid, 45.2 mg of palladium(II) acetate and 140 mg ofdi(1-adamantyl)-n-butylphosphine were added, followed by stirring at120° C. for 6 hours and then at 140° C. for 3 hours. Water was added tothis reaction liquid, suction filtration was performed, and theresulting residue was washed with ethyl acetate and hexane. This residuewas dissolved in heated toluene, followed by filtration through a filteraid filled with Celite, alumina, and Celite in this order. The obtainedsolution was concentrated and dried, and then recrystallized withtoluene to give 1.50 g of a white solid containing a target substance.

By a train sublimation method, 1.50 g of the obtained white solid wassublimated and purified. The conditions of the sublimation purificationwere such that the solid was heated under a pressure of 3.48 Pa at 280°C. while the argon gas was made to flow at a flow rate of 15 mL/min.After the purification by sublimation, a target substance was obtained(1.02 g of a white solid, collection rate: 68%). This synthesis schemeis shown in the following formula (a-1).

Analysis results by nuclear magnetic resonance (H-NMR) spectroscopy ofthe white solid obtained in the above-described reaction are shownbelow. FIG. 8 shows a ¹H-NMR chart. The results reveal that8Ph-4mDBtPBfpm, the above-described organic compound of one embodimentof the present invention represented by Structural Formula (100), wasobtained in this example.

¹H-NMR. δ (CDCl₃): 7.42 (t, 1H), 7.49-7.53 (m, 4H), 7.64-7.66 (m, 2H),7.71 (d, 2H), 7.79-7.82 (m, 2H), 7.87 (d, 1H), 7.97 (t, 2H), 8.23-8.25(m, 2H), 8.52 (s, 1H), 8.72 (d, 1H), 9.05 (s, 1H), 9.33 (s, 1H).

<<Physical Properties of 8 pH-4mDBtPBfpm>>

Next, the ultraviolet-visible absorption spectra (hereinafter, simplyreferred to as “absorption spectra”) and emission spectra of a toluenesolution and a solid thin film of 8Ph-4mDBtPBfpm were measured.

The absorption spectrum in the toluene solution was measured with anultraviolet-visible spectrophotometer (V550, produced by JASCOCorporation). The emission spectrum in the toluene solution was measuredwith a fluorescence spectrophotometer (FS920, manufactured by HamamatsuPhotonics K.K.). FIG. 9(A) shows the obtained measurement results of theabsorption spectrum and the emission spectrum of the toluene solution.The horizontal axis represents wavelength and the vertical axesrepresent absorption intensity and emission intensity.

As can be seen in FIG. 9(A), 8Ph-4mDBtPBfpm in the toluene solutionexhibited absorption peaks at approximately 335 nm, 316 nm, and 280 nmand an emission wavelength peak at 389 nm (excitation wavelength: 320nm).

In the measurement of the absorption spectrum of the solid thin film,the solid thin film formed on a quartz substrate by a vacuum evaporationmethod was used and measurement was performed with anultraviolet-visible spectrophotometer (U-4100, manufactured by HitachiHigh-Technologies Corporation). In the measurement of the emissionspectrum of the solid thin film, the solid thin film similar to theabove was used and measurement was performed with a fluorescencespectrophotometer (FS920 manufactured by Hamamatsu Photonics K.K.). FIG.9(B) shows the obtained measurement results of the absorption spectrumand emission spectrum of the solid thin film. The horizontal axisrepresents wavelength and the vertical axes represent absorptionintensity and emission intensity.

As can be seen in FIG. 9(B), 8Ph-4mDBtPBfpm of the solid thin filmexhibited absorption peaks at approximately 342 nm, 320 nm, and 243 nmand an emission wavelength peak at 412 nm (excitation wavelength: 340nm).

The organic compound of one embodiment of the present invention,8Ph-4mDBtPBfpm, has a high T1 level and thus is a host material suitablefor a phosphorescent material (guest material) which emits light in thevicinity of blue to yellow regions. Note that 8Ph-4mDBtPBfpm, theorganic compound of one embodiment of the present invention, can also beused as a host material for a substance that emits phosphorescence inthe visible region or a light-emitting substance.

Example 2 Synthesis Example 2

In this example, a synthesis method of4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-8-phenyl-[1]benzofuro[3,2-d]pyrimidine(abbreviation: 8Ph-4mDBtBPBfpm), which is an organic compound of oneembodiment of the present invention represented by Structural Formula(101) in Embodiment 1, will be described. Note that the structure of8Ph-4mDBtBPBfpm is shown below.

Step 1: Synthesis of 2-hydroxy-5-phenylbenzonitrile

Into a three-neck flask, 1.57 g of a phenylboronic acid, 2.30 g of5-bromo-2-hydroxybenzonitrile, 3.21 g of potassium carbonate, 43.5 mL oftoluene, 14.5 mL of ethanol, and 11.6 mL of water were put, they weredegassed by being stirred under reduced pressure, and the air wasreplaced with nitrogen.

To this mixture, 53.0 mg of palladium(II) acetate and 0.142 g oftris(2-methylphenyl)phosphine (abbreviation: P(o-tol)₃) were added,followed by stirring at 100° C. for 8 hours. Water was added to theobtained reaction liquid, and extraction with ethyl acetate wasperformed. The obtained organic layer was washed with water and asaturated aqueous solution of sodium chloride, and dried with magnesiumsulfate.

This mixture was subjected to gravity filtration and the filtrate wasconcentrated to give a pale brown solid. Heated toluene was added to theobtained solid and filtered through a filter aid filled with Celite,alumina, and Celite in this order. The residue precipitated at this timewas dissolved in a mixed solvent of ethyl acetate, dichloromethane, andmethanol, followed by filtration through a filter aid filled withCelite, alumina, and Celite in this order. The obtained solution wasconcentrated and dried to give 1.86 g of a target light brown solid in ayield of 82%. This synthesis scheme is shown in the following formula(b-1).

Step 2: Synthesis of ethyl 3-amino-5-phenylbenzo[b]furan-2-carboxylate

Next, 1.86 g of 2-hydroxy-5-phenylbenzonitrile, which is the targetsubstance obtained in the above Step 1, and 2.65 g of potassiumcarbonate were put into a three-neck flask, and the air was replacedwith nitrogen. To this mixture, 1.91 g of ethyl bromoacetate and 12 mLof N,N-dimethylformamide were added, followed by stirring at 100° C. for14 hours. The obtained reaction substance was put into iced water,stirred for 1 hour, and subjected to suction filtration to give aresidue. The obtained residue was washed with water to give 2.13 g of atarget brown solid in a yield of 80%. This synthesis scheme is shown inthe following formula (b-2).

Step 3: Synthesis of 8-phenyl[1]benzofuro[3,2-d]pyrimidin-4(3)-one

Next, 2.13 g of 3-amino-5-phenylbenzo[b]furan-2-carboxylate, which isthe target substance obtained in the above Step 2, and 11 mL offormamide were put into a recovery flask and heated at 150° C. To thismixture, 1.59 g of formamidine acetate was added, followed by stirringat 160° C. for 14.5 hours. Water was added to the obtained reactionsubstance, suction filtration was performed, and the resulting residuewas washed with toluene and hexane to give 1.86 g of a target lightbrown solid in a yield of 94%. This synthesis scheme is shown in thefollowing formula (b-3).

Step 4: Synthesis of 4-chloro-8-phenyl[1]benzofuro[3,2-d]pyrimidine

Next, 1.86 g of 8-phenyl[1]benzofuro[3,2-d]pyrimidin-4(3H)-one, which isthe target substance obtained in the above Step 3, and 0.05 mL ofN,N-dimethylformamide were put into a three-neck flask and stirred. Tothis mixture, 10.7 g of phosphoryl chloride was added, followed bystirring at 90° C. for 17 hours. The obtained reaction substance was putinto iced water, neutralized with sodium hydroxide and a saturatedaqueous solution of sodium bicarbonate, and stirred for 1 hour. Thismixture was subjected to suction filtration, and the resulting residuewas washed with ethanol to give 1.84 g of a target ocher solid in ayield of 92%. This synthesis scheme is shown in the following formula(b-4).

Step 5: Synthesis of4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-8-phenyl-[1]benzofuro[3,2-d]pyrimidine

Next, 1.00 g of 4-chloro-8-phenyl[1]benzofuro[3,2-d]pyrimidine, which isobtained in the above Step 4, 1.52 g of3′-(dibenzothiophen-4-yl)-1,1′-biphenyl-3-ylboronic acid, 0.997 g ofpotassium carbonate, 13.5 mL of toluene, 4.5 mL of ethanol, and 3.6 mLof water were put into a three-neck flask, they were degassed by beingstirred under reduced pressure, and the air was replaced with nitrogen.

To this mixture, 129 mg of tetrakis(triphenylphosphine)palladium(0) wasadded, followed by stirring at 100° C. for 6.5 hours. Water was added tothe obtained reaction substance, and suction filtration was performed.The obtained residue was washed with water and ethyl acetate, anddissolved in heated toluene, followed by filtration through a filter aidfilled with Celite, alumina, and Celite in this order. The obtainedsolution was concentrated and dried, and then recrystallized withtoluene to give 1.11 g of a target white solid in a yield of 53%. Thissynthesis scheme is shown in the following formula (b-5).

By a train sublimation method, 1.10 g of this white solid was sublimatedand purified. The conditions of the sublimation purification were suchthat the solid was heated under a pressure of 2.8 Pa at 295° C. whilethe argon gas was made to flow at a flow rate of 10 mL/min. After thepurification by sublimation, a target substance was obtained (0.90 g ofa light yellow solid, collection rate: 82%).

Analysis results by nuclear magnetic resonance (H-NMR) spectroscopy ofthe white solid obtained in the above-described reaction are shownbelow. FIG. 10 shows a ¹H-NMR chart. The results reveal that8Ph-4mDBtBPBfpm, the above-described organic compound of one embodimentof the present invention represented by Structural Formula (101), wasobtained in this example.

¹H-NMR. δ (CDCl₃): 7.42 (t, 1H), 7.45-7.53 (m, 4H), 7.60-7.61 (m, 2H),7.67-7.76 (m, 5H), 7.80 (t, 2H), 7.84 (d, 1H), 7.91 (t, 2H), 8.18-8.23(m, 3H), 8.51 (s, 1H), 8.63 (d, 1H), 8.97 (s, 1H), 9.31 (s, 1H).

<<Physical Properties of 8 pH-4mDBtBPBfpm>>

Next, the ultraviolet-visible absorption spectra (hereinafter, simplyreferred to as “absorption spectra”) and emission spectra of a toluenesolution and a solid thin film of 8Ph-4mDBtBPBfpm were measured.

The absorption spectrum in the toluene solution was measured with anultraviolet-visible spectrophotometer (V550, produced by JASCOCorporation). The emission spectrum in the toluene solution was measuredwith a fluorescence spectrophotometer (FS920, manufactured by HamamatsuPhotonics K.K.). FIG. 11(A) shows the obtained measurement results ofthe absorption spectrum and the emission spectrum of the toluenesolution. The horizontal axis represents wavelength and the verticalaxes represent absorption intensity and emission intensity.

As can be seen in FIG. 11(A), 8Ph-4mDBtBPBfpm in the toluene solutionexhibited absorption peaks at approximately 332 nm, 314 nm, and 280 nmand an emission wavelength peak at 390 nm (excitation wavelength: 314nm).

In the measurement of the absorption spectrum of the solid thin film,the solid thin film formed on a quartz substrate by a vacuum evaporationmethod was used and measurement was performed with anultraviolet-visible spectrophotometer (U-4100, manufactured by HitachiHigh-Technologies Corporation). In the measurement of the emissionspectrum of the solid thin film, the solid thin film similar to theabove was used and measurement was performed with a fluorescencespectrophotometer (FS920, manufactured by Hamamatsu Photonics K.K.).FIG. 11(B) shows the obtained measurement results of the absorptionspectrum and emission spectrum of the solid thin film. The horizontalaxis represents wavelength and the vertical axes represent absorptionintensity and emission intensity.

As can be seen in FIG. 11(B), 8Ph-4mDBtBPBfpm of the solid thin filmexhibited absorption peaks at approximately 340 nm, 320 nm, and 244 nmand an emission wavelength peak at 408 nm (excitation wavelength: 330nm).

The organic compound of one embodiment of the present invention,8Ph-4mDBtBPBfpm, has a high T1 level and thus is a host materialsuitable for a phosphorescent material (guest material) which emitslight in the vicinity of blue to yellow regions. Note that8Ph-4mDBtBPBfpm, the organic compound of one embodiment of the presentinvention, can also be used as a host material for a substance thatemits phosphorescence in the visible region or a light-emittingsubstance.

Example 3 Synthesis Example 3

In this example, a synthesis method of4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-2,8-diphenyl[1]benzofuro[3,2-d]pyrimidine(abbreviation: 2,8Ph-4mDBtBPBfpm), which is an organic compound of oneembodiment of the present invention represented by Structural Formula(102) in Embodiment 1, will be described. Note that the structure of2,8Ph-4mDBtBPBfpm is shown below.

Step 1: Synthesis of2,8-dichloro-4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-[1]benzofuro[3,2-d]pyrimidine

Into a three-neck flask, 1.22 g of2,4,8-trichloro[1]benzofuro[3,2-d]pyrimidine, 1.67 g of3′-(dibenzothiophen-4-yl)-1,1′-biphenyl-3-ylboronic acid, 1.02 g ofpotassium carbonate, 13.7 mL of toluene, 4.6 mL of ethanol, and 3.7 mLof water were put, they were degassed by being stirred under reducedpressure, and the air was replaced with nitrogen.

To this mixture, 78.0 mg of bis(triphenylphosphine)palladium(II)dichloride (abbreviation: Pd(PPh₃)₂Cl₂) was added, followed by stirringat 100° C. for 6.5 hours. Water was added to this reaction substance,suction filtration was performed, and the resulting residue was washedwith water, ethanol, and toluene.

This residue was dissolved in heated toluene, followed by filtrationthrough a filter aid filled with Celite, alumina, and Celite in thisorder. The obtained solution was concentrated and dried, and thenrecrystallized with toluene to give 2.06 g of a target white solid in ayield of 98%. This synthesis scheme is shown in the following formula(c-1).

Step 2: Synthesis of4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-2,8-diphenyl[1]benzofuro[3,2-d]pyrimidine

Next, 2.06 g of2,8-dichloro-4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-[1]benzofuro[3,2-d]pyrimidine,which is the target substance obtained in Step 1, 0.968 g of aphenylboronic acid, 1.09 g of cesium fluoride, and 36 mL of mesitylenewere put into a three-neck flask, they were degassed by being stirredunder reduced pressure, and the air was replaced with nitrogen.

This mixture was heated to 60° C., and 100 mg oftris(dibenzylideneacetone)dipalladium(0) and 78.3 mg of2′-(dicyclohexylphosphino)acetophenone ethylene ketal were addedthereto, followed by stirring at 100° C. for 18 hours. Water was addedto this reaction liquid, suction filtration was performed, and theresulting residue was washed with water, ethanol, and toluene. Thisresidue was dissolved in heated toluene, followed by filtration througha filter aid filled with Celite, alumina, and Celite in this order.

The obtained solution was concentrated and recrystallized with toluene,and the resulting solid was washed with a mixed solution of hexane andmethanol. The obtained solid was purified by recycling preparative HPLCto give 0.760 g of a target light yellow solid in a yield of 7.2%. Thissynthesis scheme is shown in the following formula (c-2).

Analysis results by nuclear magnetic resonance (¹H-NMR) spectroscopy ofthe light yellow solid obtained in the above-described reaction areshown below. FIG. 12 shows a ¹H-NMR chart. The results reveal that2,8Ph-4mDBtBPBfpm, the above-described organic compound of oneembodiment of the present invention represented by Structural Formula(102), was obtained in this example.

¹H-NMR. δ (CDCl₃): 7.41-7.56 (m, 8H), 7.60-7.64 (m, 2H), 7.71 (t, 1H),7.73-7.81 (m, 6H), 7.86 (d, 1H), 7.90-7.94 (m, 2H), 8.20-8.24 (m, 3H),8.59 (s, 1H), 8.74-8.77 (m, 3H), 9.10 (s, 1H).

The organic compound of one embodiment of the present invention,2,8Ph-4mDBtBPBfpm, has a high T1 level and thus is a host materialsuitable for a phosphorescent material (guest material) which emitslight in the vicinity of blue to yellow regions. Note that2,8Ph-4mDBtBPBfpm, the organic compound of one embodiment of the presentinvention, can also be used as a host material for a substance thatemits phosphorescence in the visible region or a light-emittingsubstance.

Example 4 Synthesis Example 4

In this example, a synthesis method of2,4-bis(dibenzofuran-4-yl)-8-phenyl-[1]benzofuro[3,2-d]pyrimidine(abbreviation: 8Ph-2,4DBf2Bfpm), which is an organic compound of oneembodiment of the present invention represented by Structural Formula(200) in Embodiment 1, will be described. Note that the structure of8Ph-2,4DBf2Bfpm is shown below.

Step 1: Synthesis of2,4-bis(dibenzofuran-4-yl)-8-chloro-[1]benzofuro[3,2-d]pyrimidine

Into a three-neck flask, 1.56 g of2,4,8-trichloro[1]benzofuro[3,2-d]pyrimidine, 2.42 g ofdibenzofuran-4-boronic acid, 1.58 g of potassium carbonate, 22 mL oftoluene, 7 mL of ethanol, and 5.7 mL of water were put, they weredegassed by being stirred under reduced pressure, and the air in theflask was replaced with nitrogen.

To this mixture, bis(triphenylphosphine)palladium(II) dichloride(abbreviation: Pd(PPh₃)₂Cl₂) was added, followed by stirring at 100° C.for 7 hours. Water was added to this reaction liquid, suction filtrationwas performed, and the resulting residue was washed with water, ethanol,and toluene. This residue was dissolved in heated toluene, followed byfiltration through a filter aid filled with Celite, alumina, and Celitein this order.

The obtained solution was concentrated and dried to give 2.84 g of atarget white solid in a yield of 93%. This synthesis scheme is shown inthe following formula (d-1).

Step 2: Synthesis of2,4-bis(dibenzofuran-4-yl)-8-phenyl-[1]benzofuro[3,2-d]pyrimidine

Next, 2.84 g of2,4-bis(dibenzofuran-4-yl)-8-chloro-[1]benzofuro[3,2-d]pyrimidine, whichis the target substance in Step 1, 0.78 g of a phenylboronic acid, 1.62g of cesium fluoride, and 53 mL of mesitylene were put into a three-neckflask, they were degassed by being stirred under reduced pressure, andthe air in the flask was replaced with nitrogen.

This mixture was heated to 60° C., and 0.147 g oftris(dibenzylideneacetone)dipalladium(0) and 0.115 g of2′-(dicyclohexylphosphino)acetophenone ethylene ketal were addedthereto, followed by stirring at 100° C. for 12.5 hours and then at 120°C. for 26 hours. Furthermore, 0.145 g oftris(dibenzylideneacetone)dipalladium(0) and 0.115 g of2′-(dicyclohexylphosphino)acetophenone ethylene ketal were added to thismixture, followed by stirring at 120° C. for 23.5 hours.

Water was added to this reaction liquid, suction filtration wasperformed, and the resulting residue was washed with water, ethanol, andtoluene. This residue was dissolved in heated toluene, followed byfiltration through a filter aid filled with Celite, alumina, and Celitein this order. The obtained solution was concentrated and dried, andthen recrystallized with toluene to give 1.94 g of a target white solidin a yield of 63%.

By a train sublimation method, 1.93 g of this white solid was sublimatedand purified. The conditions of the sublimation purification were suchthat the solid was heated under a pressure of 2.51 Pa at 300° C. whilethe argon gas was made to flow at a flow rate of 11 mL/min. After thepurification by sublimation, 1.73 g of a target light yellow solid wasobtained at a collection rate of 90%. This synthesis scheme is shown inthe following formula (d-2).

Analysis results by nuclear magnetic resonance (¹H-NMR) spectroscopy ofthe light yellow solid obtained in the above-described reaction areshown below. FIG. 13 shows a ¹H-NMR chart. The results reveal that8Ph-2,4DBf2Bfpm, the above-described organic compound of one embodimentof the present invention represented by Structural Formula (200), wasobtained in this example.

¹H-NMR. δ (CDCl₃): 7.38-7.45 (m, 3H), 7.49-7.55 (m, 4H), 7.58 (t, 1H),7.66 (t, 2H), 7.74 (d, 1H), 7.76-7.80 (m, 3H), 7.99 (d, 1H), 8.04 (d,1H), 8.08 (d, 1H), 8.13 (d, 1H), 8.23 (d, 1H), 8.49 (d, 1H), 8.71 (d,1H), 8.73 (s, 1H).

The organic compound of one embodiment of the present invention,8Ph-2,4DBf2Bfpm, has a high T1 level and thus is a host materialsuitable for a phosphorescent material (guest material) which emitslight in the vicinity of blue to yellow regions. Note that8Ph-2,4DBf2Bfpm, the organic compound of one embodiment of the presentinvention, can also be used as a host material for a substance thatemits phosphorescence in the visible region or a light-emittingsubstance.

Example 5

In this example, the element structures, manufacturing methods, andcharacteristics of a light-emitting element 1, which is thelight-emitting element of one embodiment of the present invention anduses4-[3-(dibenzothiophen-4-yl)phenyl]-8-phenyl-[1]benzofuro[3,2-d]pyrimidine(abbreviation: 8Ph-4mDBtPBfpm) (Structural Formula (100)) described inExample 1 in its light-emitting layer, a comparative light-emittingelement 2 which uses4,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[3,2-d]pyrimidine in itslight-emitting layer, and a comparative light-emitting element 3 whichuses8-(dibenzothiophen-4-yl)-4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-[1]benzofuro[3,2-d]pyrimidine(abbreviation: 8DBt-4mDBtPBfpm) in its light-emitting layer will bedescribed. Note that FIG. 14 illustrates the element structure of thelight-emitting elements used in this example, and Table 1 shows specificstructures. Chemical formulae of materials used in this example areshown below.

TABLE 1 First Hole-transport Light-emitting Electron- Second electrodeHole-injection layer layer layer Electron-transport layer injectionlayer electrode Light-emitting ITSO DBT3P-II:MoOx PCBBilBP *8Ph-4mDBtPBfpm NBphen LiF Al element 1 (70 nm) (2:1 50 nm) (20 nm) (20nm) (15 nm) (1 nm) (200 nm) Comparative ITSO DBT3P-II:MoOx PCBBilBP **4,8mDBtP2Bfpm NBphen LiF Al light-emitting (70 nm) (2:1 50 nm) (20 nm)(20 nm) (15 nm) (1 nm) (200 nm) element 2 Comparative ITSO DBT3P-II:MoOxPCBBilBP *** 8DBt-4mDBtPBfpm NBphen LiF Al light-emitting (70 nm) (2:150 nm) (20 nm) (20 nm) (15 nm) (1 nm) (200 nm) element 3 *8Ph-4mDBtPBfpm:PCCP:[Ir(ppy)₂(4dppy)] (0.6:0.4:0.1 40 nm) **4,8mDBtP2Bfpm:PCCP:[Ir(ppy)₂(4dppy)] (0.6:0.4:0.1 40 nm) ***8DBt-4mDBtPBfpm:PCCP:[Ir(ppy)₂(4dppy)] (0.6:0.4:0.1 40 nm)

<<Fabrication of Light-Emitting Elements>>

The light-emitting elements described in this example have a structureas illustrated in FIG. 14, in which a hole-injection layer 911, ahole-transport layer 912, a light-emitting layer 913, anelectron-transport layer 914, and an electron-injection layer 915 arestacked in this order over a first electrode 901 formed over a substrate900, and a second electrode 903 is stacked over the electron-injectionlayer 915.

First, the first electrode 901 was formed over the substrate 900. Theelectrode area was set to 4 mm² (2 mm×2 mm). A glass substrate was usedas the substrate 900. The first electrode 901 was formed to a thicknessof 70 nm using indium tin oxide containing silicon oxide (ITSO) by asputtering method.

As pretreatment, a surface of the substrate was washed with water,baking was performed at 200° C. for 1 hour, and then UV ozone treatmentwas performed for 370 seconds. After that, the substrate was transferredinto a vacuum evaporation apparatus in which the pressure was reduced toabout 10⁻⁴ Pa, vacuum baking at 170° C. for 30 minutes was performed ina heating chamber in the vacuum evaporation apparatus, and then thesubstrate was naturally cooled down for about 30 minutes.

Next, the hole-injection layer 911 was formed over the first electrode901. For the formation of the hole-injection layer 911, the pressure inthe vacuum evaporation apparatus was reduced to 10⁻⁴ Pa, and then1,3,5-tri(dibenzothiophen-4-yl)benzene (abbreviation: DBT3P-II) andmolybdenum oxide were co-evaporated such that DBT3P-II:molybdenum oxidewas equal to 2:1 (mass ratio) and the thickness was 50 nm.

Then, the hole-transport layer 912 was formed over the hole-injectionlayer 911. The hole-transport layer 912 was formed to a thickness of 20nm by evaporation using4,4′-diphenyl-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine(abbreviation: PCBBi1BP).

Next, the light-emitting layer 913 was formed over the hole-transportlayer 912.

For the light-emitting layer 913 in the light-emitting element 1,co-evaporation usingbis[2-(2-pyridinyl-KN)phenyl-κC][2-(4-phenyl-2-pyridinyl-KN)phenyl-κC]iridium(III)(abbreviation: [Ir(ppy)₂(4dppy)]) as a guest material (phosphorescentmaterial) in addition to 8Ph-4mDBtPBfpm and3,3′-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP) was performed suchthat the weight ratio was8Ph-4mDBtPBfpm:PCCP:[Ir(ppy)₂(4dppy)]=0.6:0.4:0.1. The thickness was setto 40 nm. For the comparative light-emitting element 2, co-evaporationusing [Ir(ppy)₂(4dppy)] as a guest material (phosphorescent material) inaddition to 4,8mDBtP2Bfpm and PCCP was performed such that the weightratio was 4,8mDBtP2Bfpm:PCCP:[Ir(ppy)₂(4dppy)]=0.6:0.4:0.1. Thethickness was set to 40 nm. For the comparative light-emitting element3, co-evaporation using [Ir(ppy)₂(4dppy)] as a guest material(phosphorescent material) in addition to 8DBt-4mDBtPBfpm and PCCP wasperformed such that the weight ratio was8DBt-4mDBtPBfpm:PCCP:[Ir(ppy)₂(4dppy)]=0.6:0.4:0.1. The thickness wasset to 40 nm.

Next, the electron-transport layer 914 was formed over thelight-emitting layer 913.

The electron-transport layer 914 in the light-emitting element 1 wasformed in the following manner: 8Ph-4mDBtPBfpm and2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation:NBphen) were sequentially deposited by evaporation to thicknesses of 20nm and 15 nm, respectively. The electron-transport layer 914 in thecomparative light-emitting element 2 was formed in the following manner:4,8mDBtP2Bfpm and NBphen were sequentially deposited by evaporation tothicknesses of 20 nm and 15 nm, respectively. The electron-transportlayer 914 in the comparative light-emitting element 3 was formed in thefollowing manner: 8DBt-4mDBtPBfpm and NBphen were sequentially depositedby evaporation to thicknesses of 20 nm and 15 nm, respectively.

Then, the electron-injection layer 915 was formed over theelectron-transport layer 914. The electron-injection layer 915 wasformed to a thickness of 1 nm by evaporation using lithium fluoride(LiF).

After that, the second electrode 903 was formed over theelectron-injection layer 915. The second electrode 903 was formed usingaluminum to a thickness of 200 nm by an evaporation method. In thisexample, the second electrode 903 functions as a cathode.

Through the above steps, the light-emitting elements in each of which anEL layer 902 was provided between a pair of electrodes over thesubstrate 900 were fabricated. The hole-injection layer 911, thehole-transport layer 912, the light-emitting layer 913, theelectron-transport layer 914, and the electron-injection layer 915described in the above steps were functional layers forming the EL layerin one embodiment of the present invention. Furthermore, in all theevaporation steps in the above fabrication method, an evaporation methodby a resistance-heating method was used.

The light-emitting elements fabricated as described above were sealedusing another substrate (not illustrated). At the time of the sealingusing the another substrate (not illustrated), the another substrate(not illustrated) on which a sealant that solidifies by ultravioletlight was applied was fixed onto the substrate 900 in a glove boxcontaining a nitrogen atmosphere, and the substrates were bonded to eachother such that the sealant attached to the periphery of thelight-emitting element formed over the substrate 900. At the time of thesealing, the sealant was irradiated with 365-nm ultraviolet light at 6J/cm² to be solidified, and the sealant was subjected to heat treatmentat 80° C. for 1 hour to be stabilized.

<<Operation Characteristics of Light-Emitting Elements>>

Operation characteristics of each of the fabricated light-emittingelements were measured. Note that the measurement was carried out atroom temperature (an atmosphere maintained at 25° C.). As the results ofthe operation characteristics of the light-emitting elements, thecurrent density-luminance characteristics are shown in FIG. 15, thevoltage-luminance characteristics are shown in FIG. 16, theluminance-current efficiency characteristics are shown in FIG. 17, andthe voltage-current characteristics are shown in FIG. 18.

Table 2 below shows initial values of main characteristics of each ofthe light-emitting elements at around 1000 cd/m².

TABLE 2 Current Current Power External quantum Voltage Current densityChromaticity Luminance efficiency efficiency efficiency (V) (mA)(mA/cm²) (x, y) (cd/m²) (cd/A) (lm/W) (%) Light-emitting 3.3 0.041 1.0(0.45, 0.54) 900 83 79 24 element 1 Comparative 3.4 0.054 1.3 (0.44,0.55) 1100 84 77 25 light-emitting element 2 Comparative 3.4 0.051 1.3(0.44, 0.55) 980 77 71 22 light-emitting element 3

FIG. 19 shows emission spectra of the case where current at a currentdensity of 2.5 mA/cm² was supplied to the light-emitting element 1, thecomparative light-emitting element 2, and the comparative light-emittingelement 3. As shown in FIG. 19, the emission spectra of thelight-emitting element 1, the comparative light-emitting element 2, andthe comparative light-emitting element 3 have peaks at around 558 nm,and it is suggested that each peak is derived from light emission of[Ir(ppy)₂(4dppy)] contained in the light-emitting layer 913.

Next, reliability tests were performed on the light-emitting element 1,the comparative light-emitting element 2, and the comparativelight-emitting element 3. FIG. 20 shows the results of the reliabilitytests. In FIG. 20, the vertical axis represents normalized luminance (%)with an initial luminance of 100%, and the horizontal axis representsdriving time (h) of the elements. As the reliability tests, constantcurrent driving tests where a constant current was supplied at a currentdensity of 50 mA/cm² were performed.

The results of the reliability tests revealed that the light-emittingelement 1 suffered less degradation in the initial stage of drivingbecause the time taken until the luminance is reduced by 5% from theinitial luminance (LT95) of the light-emitting element 1 was 83 hoursand those of the comparative light-emitting element 2 and thecomparative light-emitting element 3 were 51 hours and 43 hours,respectively. It is useful to use the organic compound of one embodimentof the present invention, 8Ph-4mDBtPBfpm (Structural Formula (100)), inimproving element characteristics of the light-emitting element. Notethat 4,8mDBtP2Bfpm used in the comparative light-emitting element 2 hasa structure in which dibenzothiophene is directly bonded to the8-position of a benzofuropyrimidine skeleton via a phenyl group, and8DBt-4mDBtPBfpm used in the comparative light-emitting element 3 has astructure in which dibenzothiophene is bonded to the 8-position of abenzofuropyrimidine skeleton, while 8Ph-4mDBtPBfpm used in thelight-emitting element 1 has a molecular structure which includes aphenyl group at the 8-position of a benzofuropyrimidine skeleton. Fromthe above facts, in order to suppress initial degradation, it is notthat the substituent at the 8-position of a benzofuropyrimidine skeletonmay be anything, but introducing an unsubstituted phenyl group isimportant.

Thus, when an organic compound having a structure including a phenylgroup, which is not a bulky substituent, at the 8-position of abenzofuropyrimidine skeleton or a benzothienopyrimidine skeleton likethe organic compound of one embodiment of the present invention is usedin a light-emitting element, transfer of excitation energy betweenmolecules becomes smooth, which brings about an effect on thesuppression of initial degradation of the light-emitting element.Accordingly, a reliable light-emitting element can be provided.

Example 6

In this example, a light-emitting element 4, which is the light-emittingelement of one embodiment of the present invention and uses8Ph-4mDBtPBfpm (Structural Formula (100)) described in Example 1 in itslight-emitting layer, and a comparative light-emitting element 5, whichuses 4,8mDBtP2Bfpm in its light-emitting layer, were fabricated and themeasured characteristics of the light-emitting elements are shown.

Note that the element structure of the light-emitting element 4 and thecomparative light-emitting element 5 fabricated in this example issimilar to that in FIG. 14 mentioned in Example 5, and the specificcomposition of each layer of the element structure is as shown in Table3. Chemical formulae of materials used in this example are shown below.

TABLE 3 First Hole-transport Light-emitting Electron- Second electrodeHole-injection layer layer layer Electron-transport layer injectionlayer electrode Light-emitting ITSO DBT3P-II:MoOx PCBBilBP *8Ph-4mDBtPBfpm NBphen LiF Al element 4 (70 nm) (2:1 45 nm) (20 nm) (20nm) (10 nm) (1 nm) (200 nm) Comparative light- ITSO DBT3P-II:MoOxPCBBilBP ** 4,8mDBtP2Bfpm NBphen LiF Al emitting element 5 (70 nm) (2:145 nm) (20 nm) (20 nm) (10 nm) (1 nm) (200 nm) *8Ph-4mDBtPBfpm:PCCP:[Ir(ppy)₂(mdppy)] (0.6:0.4:0.1 40 nm) **4,8mDBtP2Bfpm:PCCP:[Ir(ppy)₂(mdppy)] (0.6:0.4:0.1 40 nm)

<<Operation Characteristics of Each Light-Emitting Element>>

Operation characteristics of the fabricated light-emitting element 4 andcomparative light-emitting element 5 were measured. Note that themeasurement was carried out at room temperature (an atmospheremaintained at 25° C.).

The current density-luminance characteristics, the voltage-luminancecharacteristics, the luminance-current efficiency characteristics, andthe voltage-current characteristics of each light-emitting element areshown in FIG. 21, FIG. 22, FIG. 23, and FIG. 24, respectively.

Table 4 below shows initial values of main characteristics of each ofthe light-emitting elements at around 1000 cd/m².

TABLE 4 Current Current Power External quantum Voltage Current densityChromaticity Luminance efficiency efficiency efficiency (V) (mA)(mA/cm²) (x, y) (cd/m²) (cd/A) (lm/W) (%) Light-emitting 3.4 0.056 1.4(0.35, 0.62) 1100 76 70 21 element 4 Comparative 3.3 0.047 1.2 (0.35,0.62) 870 74 70 20 light-emitting element 5

FIG. 25 shows emission spectra of the case where current at a currentdensity of 2.5 mA/cm² was supplied to the light-emitting element 4 andthe comparative light-emitting element 5. As shown in FIG. 25, theemission spectra of the light-emitting elements have peaks at around 525nm, and it is suggested that the peaks are derived from light emissionof [Ir(ppy)₂(mdppy)] contained in the light-emitting layer 913.

Next, reliability tests were performed on the light-emitting element 4and the comparative light-emitting element 5. FIG. 26 shows the resultsof the reliability tests. In FIG. 26, the vertical axis representsnormalized luminance (%) with an initial luminance of 100%, and thehorizontal axis represents driving time (h) of the elements. As thereliability tests, constant current driving tests where a constantcurrent was supplied at a current density of 50 mA/cm² were performed.

The results of the reliability tests show that the light-emittingelement 4 which used the organic compound of one embodiment of thepresent invention, 8Ph-4mDBtPBfpm, had a suppressed initial degradationbecause the time taken until the luminance is reduced by 5% from theinitial luminance (LT95) of the light-emitting element 4 was 33 hoursand that of the comparative light-emitting element 5 which used thecomparative organic compound, 4,8mDBtP2Bfpm, was 24 hours. This is owingto the effect of the organic compound of one embodiment of the presentinvention, 8Ph-4mDBtPBfpm, having at least a phenyl group at the8-position of a benzofuropyrimidine skeleton. From the above facts, inorder to suppress initial degradation, introducing an unsubstitutedphenyl group at the 8-position of a benzofuropyrimidine skeleton isimportant. Thus, it is useful to use the organic compound of oneembodiment of the present invention in improving reliability of thelight-emitting element.

Example 7

In this example, a light-emitting element 6, which is the light-emittingelement of one embodiment of the present invention and uses4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-8-phenyl-[1]benzofuro[3,2-d]pyrimidine(abbreviation: 8Ph-4mDBtBPBfpm) (Structural Formula (101)) described inExample 2 in its light-emitting layer, a comparative light-emittingelement 7 which uses8-(dibenzothiophen-4-yl)-4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-[1]benzofuro[3,2-d]pyrimidine(abbreviation: 8DBt-4mDBtBPBfpm) in its light-emitting layer, and acomparative light-emitting element 8, which uses4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-8-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine(abbreviation: 8mDBtP-4mDBtBPBfpm) in its light-emitting layer, werefabricated and the measured characteristics of the light-emittingelements are shown.

Note that the element structure of the light-emitting element 6, thecomparative light-emitting element 7, and the comparative light-emittingelement 8 fabricated in this example is similar to that in FIG. 14mentioned in Example 5, and the specific composition of each layer ofthe element structure is as shown in Table 5. Chemical formulae ofmaterials used in this example are shown below.

TABLE 5 First Hole-transport Light-emitting Electron- Second electrodeHole-injection layer layer layer Electron-transport layer injectionlayer electrode Light-emitting ITSO DBT3P-II:MoOx PCBBilBP *8Ph-4mDBtBPBfpm NBphen LiF Al element 6 (70 nm) (2:1 45 nm) (20 nm) (20nm) (10 nm) (1 nm) (200 nm) Comparative ITSO DBT3P-II:MoOx PCBBilBP **8DBt-4mDBtBPBfpm NBphen LiF Al light-emitting (70 nm) (2:1 45 nm) (20nm) (20 nm) (10 nm) (1 nm) (200 nm) element 7 Comparative ITSODBT3P-II:MoOx PCBBilBP *** 8mDBtP-4mDBtBPBfpm NBphen LiF Allight-emitting (70 nm) (2:1 45 nm) (20 nm) (20 nm) (10 nm) (1 nm) (200nm) element 8 * 8Ph-4mDBtBPBfpm:PCCP:[Ir(ppy)₂(mdppy)] (0.5:0.5:0.1 40nm) ** 8DBt-4mDBtBPBfpm:PCCP:[Ir(ppy)₂(mdppy)] (0.5:0.5:0.1 40 nm) ***8mDBtP-4mDBtBPBfpm:PCCP:[Ir(ppy)₂(mdppy)] (0.5:0.5:0.1 40 nm)

<<Operation Characteristics of Each Light-Emitting Element>>

Operation characteristics of the fabricated light-emitting element 6,the comparative light-emitting element 7, and the comparativelight-emitting element 8 were measured. Note that the measurement wascarried out at room temperature (an atmosphere maintained at 25° C.).

The current density-luminance characteristics, the voltage-luminancecharacteristics, the luminance-current efficiency characteristics, andthe voltage-current characteristics of each light-emitting element areshown in FIG. 27, FIG. 28, FIG. 29, and FIG. 30, respectively.

Table 6 below shows initial values of main characteristics of each ofthe light-emitting elements at around 1000 cd/m².

TABLE 6 Current Current Power External quantum Voltage Current densityChromaticity Luminance efficiency efficiency efficiency (V) (mA)(mA/cm²) (x, y) (cd/m²) (cd/A) (lm/W) (%) Light-emitting 3.4 0.052 0.3(0.35, 0.62) 990 76 70 21 element 6 Comparative 3.6 0.051 1.3 (0.35,0.61) 910 71 62 20 light-emitting element 7 Comparative 3.6 0.062 1.6(0.34, 0.62) 1000 66 58 18 light-emitting element 8

FIG. 31 shows emission spectra of the case where current at a currentdensity of 2.5 mA/cm² was supplied to the light-emitting element 6, thecomparative light-emitting element 7, and the comparative light-emittingelement 8. As shown in FIG. 31, the emission spectra of thelight-emitting elements have peaks at around 523 nm, and it is suggestedthat the peaks are derived from light emission of [Ir(ppy)₂(mdppy)]contained in the light-emitting layer 913.

Next, reliability tests were performed on the light-emitting element 6,the comparative light-emitting element 7, and the comparativelight-emitting element 8. FIG. 32 shows the results of the reliabilitytests. In FIG. 32, the vertical axis represents normalized luminance (%)with an initial luminance of 100%, and the horizontal axis representsdriving time (h) of the elements. As the reliability tests, constantcurrent driving tests where a constant current was supplied at a currentdensity of 50 mA/cm² were performed.

The results of the reliability tests show that the light-emittingelement 6 which used the organic compound of one embodiment of thepresent invention, 8Ph-4mDBtBPBfpm, had a suppressed initial degradationcompared with the light-emitting element 7 which used the comparativeorganic compound, 8DBt-4mDBtBPBfpm, and the comparative light-emittingelement 8 which used the comparative organic compound,8mDBtP-4mDBtBPBfpm. This is owing to the effect of the organic compoundof one embodiment of the present invention, 8Ph-4mDBtBPBfpm, having aphenyl group at the 8-position of a benzofuropyrimidine skeleton. Fromthe above facts, in order to suppress initial degradation, introducingan unsubstituted phenyl group at the 8-position of a benzofuropyrimidineskeleton is important. Thus, it is useful to use the organic compound ofone embodiment of the present invention in improving reliability of thelight-emitting element.

Reference Synthesis Example 1

In this reference synthesis example, a specific example of synthesizingthe organic compound represented by the structural formula below andused for the comparative light-emitting element 7 of this example,8-(dibenzothiophen-4-yl)-4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-[1]benzofuro[3,2-d]pyrimidine(abbreviation: 8DBt-4mDBtBPBfpm) (Structural Formula (300)), will bedescribed.

Into a three-neck flask, 7.00 g of8-chloro-4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-[1]benzofuro[3,2-d]pyrimidine,3.56 g of dibenzothiophene-4-boronic acid, 0.281 g of2′-(dicyclohexylphosphino)acetophenone ethylene ketal, 6.00 g of cesiumfluoride, and 65 mL of mesitylene were put, they were degassed by beingstirred under reduced pressure, and the air was replaced with nitrogen.

To this mixture, 0.359 g of tris(dibenzylideneacetone)dipalladium(0)(Pd₂(dba)₃) was added, followed by stirring at 120° C. for 1 hour. Tothis mixture, 65 mL of degassed mesitylene was added, and stirring wasperformed at 120° C. for 9.5 hours. Furthermore, 30 mL of degassedmesitylene was added to the mixture and stirring was performed at 120°C. for 7 hours. To this mixture, 0.360 g of Pd₂(dba)₃ and 0.284 g of2′-(dicyclohexylphosphino)acetophenone ethylene ketal were added, andstirring was performed at 130° C. for 15 hours, and then at 140° C. for6 hours.

To this mixture, 2.37 g of dibenzothiophene-4-boronic acid, 0.359 g ofPd₂(dba)₃, and 0.283 g of 2′-(dicyclohexylphosphino)acetophenoneethylene ketal were added, and stirring was performed at 140° C. for 40hours. Water was added to the obtained reaction substance, suctionfiltration was performed, and the resulting residue was washed withwater and ethyl acetate. This residue was dissolved in heated toluene,followed by filtration through a filter aid filled with Celite, alumina,and Celite in this order. The obtained solution was concentrated anddried, and then recrystallized with toluene to give 5.56 g of a targetsubstance (yield: 62%, white solid).

By a train sublimation method, 1.95 g of this white solid was sublimatedand purified. The conditions of the sublimation purification were suchthat the solid was heated under a pressure of 2.8 Pa at 355° C. whilethe argon gas was made to flow at a flow rate of 15 mL/min. After thepurification by sublimation, 1.46 g of a target pale brown substance wasobtained at a collection rate of 75%. The synthesis scheme is shown inthe following formula (e-1).

Analysis results by nuclear magnetic resonance (¹H-NMR) spectroscopy ofthe pale brown solid obtained as described above are shown below. It wasfound that 8DBt-4mDBtBPBfpm was obtained.

¹H-NMR. δ (CDCl₃): 7.47-7.51 (m, 4H), 7.59-7.65 (m, 4H), 7.70 (t, 1H),7.76-7.87 (m, 6H), 7.95 (d, 1H), 8.09 (d, 1H), 8.21-8.24 (m, 5H),8.66-8.68 (m, 2H), 9.01 (s, 1H), 9.34 (s, 1H).

Reference Synthesis Example 2

In this reference synthesis example, a specific example of synthesizingthe organic compound represented by the structural formula below andused for the comparative light-emitting element 8 of this example,4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-8-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine(abbreviation: 8mDBtP-4mDBtBPBfpm) (Structural Formula (301)), will bedescribed.

Into a three-neck flask, 1.23 g of8-chloro-4-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]-[1]benzofuro[3,2-d]pyrimidine,0.837 g of 3-(dibenzothiophene-4-yl)phenylboronic acid, 49.2 mg of2′-(dicyclohexylphosphino)acetophenone ethylene ketal, 1.03 g of cesiumfluoride, and 30 mL of mesitylene were put, they were degassed by beingstirred under reduced pressure, and the air was replaced with nitrogen.

To this mixture, 63.2 mg of tris(dibenzylideneacetone)dipalladium(0)(Pd₂(dba)₃) was added, and stirring was performed at 100° C. for 20.5hours. To this mixture, 49.1 mg of2′-(dicyclohexylphosphino)acetophenone ethylene ketal and 63.0 mg ofPd₂(dba)₃ were added, followed by stirring at 120° C. for 23 hours.Furthermore, 52.3 mg of 2′-(dicyclohexylphosphino)acetophenone ethyleneketal and 62.4 mg of Pd₂(dba)₃ were added to this mixture, and stirringwas performed at 140° C. for 21 hours.

Water was added to the obtained reaction substance, suction filtrationwas performed, and the resulting residue was washed with water and ethylacetate. This residue was dissolved in heated toluene, followed byfiltration through a filter aid filled with Celite, alumina, and Celitein this order. The obtained solution was concentrated and dried, andthen recrystallized with toluene to give 0.70 g of a target substance(yield: 40%, white solid).

By a train sublimation method, 0.70 g of this white solid was sublimatedand purified. The conditions of the sublimation purification were suchthat the solid was heated under a pressure of 2.8 Pa at 375° C. whilethe argon gas was made to flow at a flow rate of 10 mL/min. After thepurification by sublimation, 0.54 g of a target yellowish white solidwas obtained at a collection rate of 77%. The synthesis scheme is shownin the following formula (f-1).

Analysis results by nuclear magnetic resonance (¹H-NMR) spectroscopy ofthe yellowish white solid obtained as described above are shown below.It was found that 8mDBtP-4mDBtBPBfpm was obtained.

¹H-NMR. δ (CDCl₃): 7.45-7.52 (m, 4H), 7.59-7.63 (m, 4H), 7.76-7.70 (m,2H), 7.75 (t, 1H), 7.79-7.82 (m, 5H), 7.85 (d, 1H), 7.87-7.89 (m, 1H),8.02 (d, 1H), 8.10 (s, 1H), 8.19-8.23 (m, 5H), 8.62 (s, 1H), 8.65 (d,1H), 8.98 (s, 1H), 9.32 (s, 1H).

Example 8 Synthesis Example 5

In this example, a synthesis method of5-[3-(8-phenyl[1]benzofuro[3,2-d]pyrimidin-4-yl)phenyl]-5H-[1]benzothieno[3,2-c]carbazole(abbreviation: 8Ph-4mBTczPBfpm), which is an organic compound of oneembodiment of the present invention represented by Structural Formula(117) in Embodiment 1, will be described. Note that the structure of8Ph-4mBTczPBfpm is shown below.

<Synthesis of 8Ph-4mBTczPBfpm>

Into a three-neck flask, 0.85 g of4-chloro-8-phenyl[1]benzofuro[3,2-d]pyrimidine, 1.31 g of3-(5H-benzothieno[3,2-c]carbazol-5-yl)phenyboronic acid, 0.83 g ofpotassium carbonate, 11.2 mL of toluene, 3.8 mL of ethanol, and 3 mL ofwater were put, they were degassed by being stirred under reducedpressure, and the air in the flask was replaced with nitrogen. To thismixture, 105 mg of tetrakis(triphenylphosphine)palladium(0) was added,followed by stirring at 100° C. for 15 hours. Water was added to thisreaction substance, suction filtration was performed, and the resultingresidue was washed with water, ethanol, and toluene. The obtainedresidue was dissolved in heated toluene, followed by filtration througha filter aid filled with Celite, alumina, and Celite in this order. Theobtained solution was concentrated and dried, and then recrystallizedwith toluene to give 1.35 g of a target yellow solid in a yield of 75%.

By a train sublimation method, 1.16 g of the obtained yellow solid wassublimated and purified. The conditions of the sublimation purificationwere such that the solid was heated under a pressure of 2.61 Pa at 310°C. while the argon gas was made to flow at a flow rate of 10 mL/min.After the purification by sublimation, 0.95 g of a target yellowsubstance was obtained at a collection rate of 82%. This synthesisscheme is shown in the following formula (g-1).

Analysis results by nuclear magnetic resonance (H-NMR) spectroscopy ofthe yellow solid obtained in the above-described reaction are shownbelow. FIG. 33 shows a H-NMR chart. The results reveal that8Ph-4mBTczPBfpm, the above-described organic compound of one embodimentof the present invention represented by Structural Formula (117), wasobtained in this example.

¹H-NMR. δ (CDCl₃): 9.32 (s, 1H), 8.95 (s, 1H), 8.80 (d, 1H), 8.52 (s,1H), 8.38 (d, 1H), 8.24 (d, 2H), 8.02 (d, 1H), 7.97-7.92 (m, 2H), 7.87(d, 1H), 7.76 (d, 1H), 7.71-7.64 (m, 4H), 7.57-7.46 (m, 6H), 7.41 (t,1H).

Example 9

In this example, a light-emitting element 9, which is the light-emittingelement of one embodiment of the present invention and uses8Ph-2,4DBf2Bfpm (Structural Formula (200)) described in Example 4, PCCP,and [Ir(ppy)₂(mdppy)] in its light-emitting layer, was fabricated andthe measured characteristics of the light-emitting element are shown.

Note that the element structure of the light-emitting element 9fabricated in this example is similar to that in FIG. 14 mentioned inExample 5, and the specific composition of each layer of the elementstructure is as shown in Table 7. Chemical formulae of materials used inthis example are shown below.

TABLE 7 First Hole-transport Light-emitting Electron- Second electrodeHole-injection layer layer layer Electron-transport layer injectionlayer electrode Light-emitting ITSO DBT3P-II:MoOx PCBBilBP *8Ph-2,4DBf2Bfpm NBphen LiF Al element 9 (70 nm) (2:1 45 nm) (20 nm) (20nm) (10 nm) (1 nm) (200 nm) * 8Ph-2,4DBf2Bfpm:PCCP:[Ir(ppy)₂(mdppy)](0.5:0.5:0.1 40 nm)

<<Operation Characteristics of Light-Emitting Element 9>>

Operation characteristics of the fabricated light-emitting element 9were measured. Note that the measurement was carried out at roomtemperature (an atmosphere maintained at 25° C.).

The current density-luminance characteristics, the voltage-luminancecharacteristics, the luminance-current efficiency characteristics, andthe voltage-current characteristics of the light-emitting element 9 areshown in FIG. 34, FIG. 35, FIG. 36, and FIG. 37, respectively.

Table 8 below shows initial values of main characteristics of thelight-emitting element 9 at around 1000 cd/m².

TABLE 8 Current Current Power External quantum Voltage Current densityChromaticity Luminance efficiency efficiency efficiency (V) (mA)(mA/cm²) (x, y) (cd/m²) (cd/A) (lm/W) (%) Light-emitting 3.4 0.044 1.1(0.37, 0.60) 790 72 66 20 element 9

FIG. 38 shows emission spectra of the case where current at a currentdensity of 2.5 mA/cm² was supplied to each light-emitting element. Asshown in FIG. 38, the emission spectra of the light-emitting element 9have peaks at around 525 nm, and it is suggested that the peaks arederived from light emission of [Ir(ppy)₂(mdppy)] contained in thelight-emitting layer 913.

REFERENCE NUMERALS

101: first electrode, 102: second electrode, 103: EL layer, 103 a, 103b: EL layer, 104, 104 a, 104 b: charge-generation layers, 111, 111, 111b: hole-injection layers, 112, 112 a, 112 b: hole-transport layers, 113,113 a, 113 b, 113 c: light-emitting layers, 114, 114 a, 114 b:electron-transport layers, 115, 115 a, 115 b: electron-injection layers,200R, 200G, 200B: optical path lengths, 201: first substrate, 202:transistor (FET), 203R, 203G, 203B, 203W: light-emitting elements, 204:EL layer, 205: second substrate, 206R, 206G, 206B: color filter, 206R′,206G′, 206B′: color filter, 207: first electrode, 208: second electrode,209: black layer (black matrix), 210R, 210G: conductive layer, 301:first substrate, 302: pixel portion, 303: driver circuit portion (sourceline driver circuit), 304 a, 304 b: driver circuit portion (gate linedriver circuits), 305: sealant, 306: second substrate, 307: lead wiring,308: FPC, 309: FET, 310: FET, 311: FET, 312: FET, 313: first electrode,314: insulator, 315: EL layer, 316: second electrode, 317:light-emitting element, 318: space, 900: substrate, 901: firstelectrode, 902: EL layer, 903: second electrode, 911: hole-injectionlayer, 912: hole-transport layer, 913: light-emitting layer, 914:electron-transport layer, 915: electron-injection layer, 4000: lightingdevice, 4001: substrate, 4002: light-emitting element, 4003: substrate,4004: first electrode, 4005: EL layer, 4006: second electrode, 4007:electrode, 4008: electrode, 4009: auxiliary wiring, 4010: insulatinglayer, 4011: sealing substrate, 4012: sealant, 4013: desiccant, 4200:lighting device, 4201: substrate, 4202: light-emitting element, 4204:first electrode, 4205: EL layer, 4206: second electrode, 4207:electrode, 4208: electrode, 4209: auxiliary wiring, 4210: insulatinglayer, 4211: sealing substrate, 4212: sealant, 4213: barrier film, 4214:planarization film, 5101: light, 5102: wheel, 5103: door, 5104: displayportion, 5105: steering wheel, 5106: shifter, 5107: seat, 5108: innerrearview mirror, 7000: housing, 7001: display portion, 7002: seconddisplay portion, 7003: speaker, 7004: LED lamp, 7005: operation key,7006: connection terminal, 7007: sensor, 7008: microphone, 7009: switch,7010: infrared port, 7011: recording medium reading portion, 7014:antenna, 7015: shutter button, 7016: image receiving portion, 7018:stand, 7021: external connection portion, 7022, 7023: operation buttons,7024: connection terminal, 7025: band, 7026: microphone, 7027: iconindicating time, 7028: another icon, 7029: sensor, 7030: speaker, 7052,7053, 7054: information, 9310: portable information terminal, 9311:display portion, 9312: display region, 9313: hinge, 9315: housing

1. An organic compound represented by General Formula (G1):

wherein Q represents oxygen or sulfur, wherein A is a group having 12 to100 carbon atoms in total and includes one or more of a benzene ring, anaphthalene ring, a fluorene ring, a phenanthrene ring, a triphenylenering, a heteroaromatic ring including a dibenzothiophene ring, aheteroaromatic ring including a dibenzofuran ring, a heteroaromatic ringincluding a carbazole ring, a benzimidazole ring, and a triphenylaminestructure, and wherein R¹ represents hydrogen, an alkyl group having 1to 6 carbon atoms, a substituted or unsubstituted monocyclic saturatedhydrocarbon having 5 to 7 carbon atoms, a substituted or unsubstitutedpolycyclic saturated hydrocarbon having 7 to 10 carbon atoms, asubstituted or unsubstituted aryl group having 6 to 13 carbon atoms, ora substituted or unsubstituted heteroaryl group having 3 to 12 carbonatoms.
 2. An organic compound represented by General Formula (G2):

wherein Q represents oxygen or sulfur, wherein α represents asubstituted or unsubstituted phenylene group, wherein n represents aninteger of 0 to 4, wherein Ht_(uni) represents a skeleton having ahole-transport property, and wherein R¹ represents hydrogen, an alkylgroup having 1 to 6 carbon atoms, a substituted or unsubstitutedmonocyclic saturated hydrocarbon having 5 to 7 carbon atoms, asubstituted or unsubstituted polycyclic saturated hydrocarbon having 7to 10 carbon atoms, a substituted or unsubstituted aryl group having 6to 13 carbon atoms, or a substituted or unsubstituted heteroaryl grouphaving 3 to 12 carbon atoms.
 3. The organic compound according to claim2, wherein the organic compound is represented by General Formula (G3):


4. The organic compound according to claim 2, wherein the organiccompound is represented by General Formula (G4):


5. The organic compound according to claim 2, wherein the Ht_(uni) hasany one of a pyrrole ring structure, a furan ring structure, or athiophene ring structure.
 6. The organic compound according to claim 2,wherein the Ht_(uni) is represented by any one of General Formulae(Ht-1) to (Ht-26) below:

wherein Q represents oxygen or sulfur, wherein R² to R⁷¹ each represent1 to 4 substituents and each independently represent any one ofhydrogen, an alkyl group having 1 to 6 carbon atoms, and a substitutedor unsubstituted phenyl group, and wherein Ar¹ represents a substitutedor unsubstituted aryl group having 6 to 13 carbon atoms.
 7. An organiccompound represented by any one of Structural Formulae (100), (101),(102), (117), and (200):


8. A light-emitting element using the organic compound according toclaim
 1. 9. A light-emitting element comprising an EL layer between apair of electrodes, wherein the EL layer comprises the organic compoundaccording to claim
 1. 10. A light-emitting element comprising an ELlayer between a pair of electrodes, wherein the EL layer comprises alight-emitting layer, and wherein the light-emitting layer comprises theorganic compound according to claim
 1. 11. A light-emitting elementcomprising an EL layer between a pair of electrodes, wherein the ELlayer comprises a light-emitting layer, and wherein the light-emittinglayer comprises the organic compound according to claim 1, and aphosphorescent material.
 12. A light-emitting element comprising an ELlayer between a pair of electrodes, wherein the EL layer comprises alight-emitting layer, and wherein the light-emitting layer comprises theorganic compound according to claim 1, a phosphorescent material, and acarbazole derivative.
 13. A light-emitting element according to claim12, wherein the carbazole derivative is a bicarbazole derivative.
 14. Alight-emitting device comprising: the light-emitting element accordingto claim 8; and at least one of a transistor and a substrate.
 15. Anelectronic device comprising: the light-emitting device according toclaim 14; and at least one of a microphone, a camera, an operationbutton, an external connection portion, and a speaker.
 16. Alightingdevice comprising: the light-emitting element according to claim 8; andat least one of a housing, a cover, and a support base.
 17. Alight-emitting element using the organic compound according to claim 2.18. A light-emitting element comprising an EL layer between a pair ofelectrodes, wherein the EL layer comprises a light-emitting layer, andwherein the light-emitting layer comprises the organic compoundaccording to claim
 2. 19. A light-emitting element comprising an ELlayer between a pair of electrodes, wherein the EL layer comprises alight-emitting layer, and wherein the light-emitting layer comprises theorganic compound according to claim 2, a phosphorescent material, and acarbazole derivative.
 20. A light-emitting element according to claim19, wherein the carbazole derivative is a bicarbazole derivative.